Answer:
1. B
2. D
Explanation:
1. Radioactive decay occurs when a radioactive particle cannot maintain a high energy state due to its own weight. When a radioactive element (eg. Uranium) undergoes radioactive decay, its product/s (following the previous example, Uranium decays into Thorium) are more stable than its reactants.
The question might remain that after Uranium decays to Thorium, where does the extra mass go? The extra mass is released as an alpha particle, and through this process, a lot of energy is released as gamma radiation.
Hence, the answer is:
During radioactive decay, atoms break down releasing particles or energy.
2. The half-life of an element is referred to as:
The length of time taken for one half of the radioactive atoms in a sample to decay.
Hence, since the question states the definition of a half-life, the answer is D.
The correct answer is (b) 'During radioactive decay, atoms break down, releasing particles or energy.' And, the term for the time it takes for one-half of the radioactive atoms in a sample to decay is (d) 'half-life.'
Explanation:The true statement about radioactive decay is option (b), 'during radioactive decay, atoms break down, releasing particles or energy.' Radioactive decay is a spontaneous process where an unstable atomic nucleus loses energy by emitting radiation, such as an alpha particle, beta particle with neutrino or only a neutrino with case of Electron Capture, or a gamma ray. The other options do not accurately describe this process.
The term referring to the time it takes for one-half of the radioactive atoms in a sample of a radioactive element to decay is option (d), 'half-life.' Half-life is commonly used in nuclear physics and chemistry, and it provides us with a measure of the time scale on which radioactive decay processes occur.
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Which electromagnetic wave enables us to see objects?
a-infrared rays
b-visible light
c-ultraviolet light
d-gamma rays
Answer: The correct answer is "visible rays".
Explanation:
Electromagnetic wave: In electromagnetic wave, both the electric fields and the magnetic field are directed in the direction of the propagation of the electromagnetic wave. Electromagnetic wave travels in vacuum.
It travels with the speed of the light.
For example, X-rays, gamma rays, infrared rays and visible region.
The electromagnetic spectrum consists of visible region and an invisible region.
Visible region of the electromagnetic can be seen by naked eyes. Its range is 400 nm to 700 nm.
We are unable to see infrared rays, ultraviolet light and gamma rays.
Therefore, the correct option is (b).
Describe Earth's three global wind belts
Final answer:
Earth's global wind belts, consisting of the Trade Winds, Westerlies, and Polar Easterlies, are formed by the unequal heating of the atmosphere and the Earth's rotation.
Explanation:
Earth's three global wind belts are crucial components of the planet's climate system and are largely responsible for the distribution of precipitation across different regions. The global wind belts are:
Trade Winds: These winds are found nearest to the equator and are characterized by their persistent direction towards the west in both hemispheres.Westerlies: Located in the mid-latitudes between 30° and 60° N and S, these winds predominantly flow towards the east.Polar Easterlies: Found in the polar regions close to the north and south poles, these winds flow outwards from the polar high-pressure areas towards lower latitudes.These wind belts are created due to the unequal heating of the Earth's atmosphere, with more solar radiation striking the equator than the poles, combined with the Earth's rotation which gives rise to the Coriolis effect. This results in a system of atmospheric circulation cells, which generate the prevalent wind patterns.
an object is shot straight upward from sea level with an initial velocity of 250 ft/sec.
a)assuming that gravity is the only force acting on the object, give an upper estimate for it's velocity after 5 seconds has elapsed. use g=32 ft/sec^2 for gravitational acceleration.
b) using delta t=1 sec, find a lower estimate for the height attained after 5 seconds. ...?
Answer:
.a 90 ft/sec b. s=400ft
Explanation:
when an object is shot straight upward, the force of gravity which is the earth magnetic pull on an object to its center, acts on it
The basic parameters to be considered are
a=-g, -32ft/sec
s=distance/height attained by the object during its motion against gravity
t=time ,secs
u=initial velocity
V=final velocity ft/sec
from newtons equation of motion,
a) V = u + g*t
So V = 250+ -32*5= 90 ft/sec
it's velocity after 5 seconds has elapsed is 90 ft/sec
b) s = [tex]s=ut+\frac{1}{2} *at^{2}[/tex]
[tex]s=250*5+\frac{1}{2}-32 *5^{2}[/tex]
s=400ft
the height attained after 5 seconds. ..s=400ft
With what magnitude of force does a ball of mass 0.75 kilograms need to be hit so that it accelerates at the rate of 25 meters/ second 2 ? Assume that the ball undergoes motion along a straight line.
A. 10 newtons
B. 19 newtons
C. 33.3 newtons
D. 40 newtons
The force required to accelerate a 0.75 kg ball at a rate of 25 m/s^2 is approximately 19 newtons, calculated using Newton's second law of motion.
Explanation:To calculate the required force to make the ball accelerate at the given rate, we need to use Newton's second law of motion, which states that the force applied on an object is equal to its mass times its acceleration (F=ma). To find the force, we multiply the mass of the ball (0.75 kg) by the acceleration (25 m/s^2).
This gives us a force of 18.75 newtons. None of the provided options match this exact answer; the closest option is B. 19 newtons, so we would select this as the best answer with the understanding that it has been rounded.
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-If an atom has 5 protons, 5 neutrons, and 3 electrons, what is the atom's charge?
A. +2
B. -2
C. 0
D. -3 ...?
Let's see the charge of each particle first:
- proton: charge +1
- neutron: charge 0
- electron: charge -1
We have 5 protons, 5 neutrons and 3 electrons, so the total charge of the atom is:
[tex] Q=5 \cdot (+1) + 5 \cdot (0) + 3 \cdot (-1) =5+0-3=+2 [/tex]
So, the correct answer is
A. +2
On the basis of electronegativity, which of these pairs of elements is most likely to form monatomic ions?
K and Rb
Ba and Ca
Na and K
Cl and Na
if you relate the Doppler effect on sound to the color of light waves, a police car would be the color (A.yellow B.red C.green D.blue) as it approaches and the color (A.red B.violet C.blue D.green) as it recedes away from the observer.
The Doppler effect says that the observed wavelength is shortened
when the source is approaching the observer, and lengthened when
the source is receding from the observer.
All we can say about the police car and its siren is that the sound/color
has a shorter wavelength as it approaches us, and a longer wavelength
as it recedes.
Any of these pairs of answers would say that:
A -- A
C -- A
D -- A
or
D -- D
For each of these pairs, the second wavelength is longer than the first one.
(We don't know which pair is the actual one, because we don't know the actual color of the police car.)
If we relate the Doppler effect on sound to the color of light waves, a police car would be the color blue as it approaches and the color red as it recedes away from the observer.
What is the Doppler effect?The Doppler effect is a phenomenon that occurs when two objects move closer or farther apart, increasing (or decreasing) the frequency of sound, light, or other waves.
The Doppler effect is to sound waves as well for the light waves
The apparent shift in the frequency of the light that the observer perceives as a result of relative motion between the source of the light and the observer is known as the Doppler effect of light.
However, the equations for the Doppler shift for sound waves vary significantly depending on whether the source, the observer, or the air is moving. Light doesn't need a medium to travel, and the observer and source's relative speeds are the only factors affecting the Doppler shift for light.
A police car would appear blue as it approaches as there is an increase in frequency resulting in the decrease in the wavelength of light known as the blue shift.
similarly, it appears red as it moves away from the observer because of the decrease in the frequency resulting increase in the wavelength of the light known as the redshift.
Thus, If the Doppler effect on sound may be compared to the color of light waves, then a police car would appear blue as it approaches and red as it moves away from the observer.
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Given theta = 7pi/6, find (sec theta, cos theta) ...?
What force makes a marble roll across level ground eventually come to a stop?
In order for a solution to form
a)one substance must dissolve in another.
b)a solid must dissolve in liquid.
c)the solvent must be water.
d)a gas must dissolve in a liquid.
Answer:
a) one substance must dissolve in another.
Explanation:
A solution is mixture in which a substance (solid, liquid or gas) dissolves in a liquid. A salt dissolved in water is an example solid dissolved in liquid. Ammonia dissolved in water is an example of liquid in liquid and oxygen dissolved in water is an example gas dissolved in liquid.
The substance being dissolved is known as solute and the liquid in which solute is known as solvent.
Predict the change that must occur in the electron configuration, if each of the following atoms is to achieve a noble gas configuration.
I need help with nitrogen. I know it gains 3 electrons. so that would make it a ____ ion?
Nitrogen attains the noble gas structure by gaining three electrons.
Stability of atoms has been associated with an atom having two or eight electrons in its outermost shell. This generally referred to as the octet rule. The octet rule is the basis for predicting the stability of atoms.
Nitrogen has an electron configuration of 1s2 2s2 2p3 in the ground state. However, when it accepts three electrons to form the stable nitride ion N^3-, its electron configuration becomes 1s2 2s2 2p6.
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The vibrations produced by a jackhammer are used to break up pavement. What type of waves did/does the jackhammer produce into the ground? ...?
The jackhammer produces primarily P-waves (compression waves) and S-waves (shear waves) that transfer energy into the ground, causing the pavement to break up. P-waves involve particle motion parallel to wave direction, while S-waves involve perpendicular particle motion. These waves are efficient in fracturing solid materials.
The vibrations produced by a jackhammer that are used to break up pavement generate seismic waves, specifically compression waves and shear waves.
A compression wave, also known as a P-wave (primary wave), is characterized by the motion of particles parallel to the direction of wave propagation. In other words, the material through which the wave passes is alternately compressed and expanded along the direction of the wave.
In contrast, a shear wave, or S-wave (secondary wave), involves particle motion that is perpendicular to the direction of wave propagation. This type of wave causes materials to move up and down or side to side.
When the jackhammer strikes the pavement, it primarily generates these two types of body waves, transferring energy into the ground to fracture and break up the solid material effectively.
Why does friction never speed up an object?
If you carry out an experiment measuring the weight and mass of objects in one particular location on the earth, what relation will you find between weight and mass in your measurements?
A. They are equal.
B. Weight is directly proportional to mass.
C.Weight is inversely proportional to mass.
D. Mass equals weight times acceleration due to gravity.
How far will a car travel, thatis moving at 20.00 m/s for 15.00 seconds?
why are the coldest places on earth found near the poles
The coldest places on Earth are at the poles because they are farthest from the sun, receive the least amount of sunlight, and experience months of darkness during the winter. This is compounded by the axial tilt of the Earth.
Explanation:The coldest places on Earth are found near the poles due to the planet's axial tilt and distance from the sun. The Earth tilts at an angle of 23.5 degrees, which means that sunlight is not evenly distributed across its surface. The poles, being the furthest points from the equator, receive the least amount of sunlight and hence are the coldest.
Moreover, the Polar Regions are in continuous darkness for six months of the year during the winter season which contributes to the extreme cold. For example, at the South Pole on June 21, all places within 23° of the South Pole do not see the sun at all for 24 hours. These regions do not get the chance to warm up, leading to freezing temperatures and icy conditions.
It is also important to note that the Earth acts like a large bar magnet with its magnetic poles near the geographic poles. This does not have a direct impact on temperature, but it is a noteworthy feature of the poles.
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One result of wave refraction is that _____.
wave energy is concentrated on headlands projecting into the water
wave energy is largely dissipated before the waves reach shore
wave energy is concentrated in the recessed areas between headlands
headlands are enlarged by sediment deposited on their seaward side
One result of wave refraction is that wave energy is concentrated on headlands projecting into the water. Refraction of waves involves a change in the direction of waves as they pass from one medium to another.
Explanation:
Refraction of waves comprises a change in the management of waves as they traverse from one medium to different. Refraction, or the bending of the track of the waves, is conducted by a transition toward speed and wavelength of the waves.
A metal conduit will be used as a pathway for wiring through a concrete block. The conduit is a 4 foot long rod with an outer diameter of 2.2 inches and an inner diameter of 2 inches. What is the volume of metal in the conduit in cubic centimeters? ...?
Answer:[tex]510. 12 cm^3[/tex]
The volume of a cylindrical conduit, [tex]V=\pi (r_2^2-r_1^2) h[/tex]
where [tex]r_1[/tex] is the inner radius, [tex]r_2[/tex] is the outer radius, h is the length.
First of all, we would covert each parameter into centimeters.
length of the conduit, [tex] h=4 ft=4\times 30.48 cm=121.92 cm[/tex]
outer radius, [tex]r_1=2.2/2 in =1.1 in= 1.1\times 2.54 cm=2.79 cm[/tex]
inner radius, [tex]r_1=2/2 in =1 in= 2.54 cm[/tex]
Insert the values in the volume formula,
[tex]V=3.14 \times (2.79^2-2.54^2) \times 121.92 cm^3=510. 12 cm^3[/tex]
Hence, the volume of metal in the conduit is 510. 12 cubic centimeters.
Which one of the following scenarios accurately describes a condition in which resonance can occur?
End of exam
A. A person is holding a tuning fork on one end of a football field and another person is holding a separate tuning fork on the opposite end of the field. B. A pipe's length is equal to 1∕2 of the wavelength of the sound waves produced by a tuning fork vibrating over one end of the pipe that's open to the air at both ends.
C. A vibrating tuning fork is struck and begins to vibrate as the object used to strike it is placed away from the tuning fork. D. A column of air has a height equal to 1∕8 of the wavelength of the sound waves produced by a tuning fork vibrating over the column of air in an open pipe that's partially immersed in water.
Answer:
B) A pipe's length is equal to 1/2 of the wavelength of the sound wave produced by a tuning fork vibrating over one end of the pipe that is open to the air at both ends.
Explanation:
Resonance occur when one object vibrating at the same frequency of another object force that object into vibration at a greater amplitude.
Let's consider a resonance tube partially filled filled with water and force into vibration by a tuning fork. The tuning fork will force the air inside the tube into resonance. As the tines of the tuning fork vibrate at their own natural frequency they create sound wave that impinge upon the opening of the resonance tube. These impinging sound wave produced by the tuning fork will force the air inside the resonance tube to vibrate at the same frequency of the tuning fork
The word resonance from the Latin word means resound - i.e to sound out together with a louder sound.
A circuit has a resistance of 2.5 Ω and is powered by a 12.0 V battery. The current in the circuit, to the nearest tenth
Answer:
The electric current in the circuit is 4.8 A.
Explanation
What is electric current?The number of charge passing through unit cross-sectional area of a conductor in one second, is called electric current. It is denoted by (i) and it is measured in Ampere.
Given data is:
Resistance (R)= 2.5 ΩPotential difference of battery (V)= 12 V
By using formula, [tex]V =i.R[/tex]⇒ [tex]i =\frac{V}{R}[/tex]
On putting values,
[tex]i = \frac{12}{2.5}[/tex]
[tex]i = \frac{120}{25} = 4.8A[/tex]
Hence the current in the circuit is 4.8 A
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According to newton's first law, what is required to make an object slow down?
A computer base unit of mass 7.5 kg is dragged along a smooth desk. If the normal contact force is 23N and the tension in the arm of the person dragging it acts at 23 degrees to the horizontal, then what is the total tension in the person's arms? ...?
Answer:
Total tension in the person's arm = 58.82 N
Explanation:
Normal Contact Force: Normal contact force is the vertical component of the contact force that is perpendicular to the surface that an object makes contact with.
As shown in fig.1 in the diagram on the attached file below.
The Normal contact force (R) = Tsinθ = The vertical component of T
Where T = Total tension in the person's arm (N), θ = angle of inclination to the horizontal.
∴ R = Tsinθ
T = R/sinθ where R= 23N, θ =23°
T = 23/sin23° = 23/0.391
T = 58.82 N
∴ Total tension in the person's arm = 58.52 N
We have that from the Question, it can be said that the total tension in the person's arms is
Ft=129N
From the Question we are told
A computer base unit of mass 7.5 kg is dragged along a smooth desk. If the normal contact force is 23N and the tension in the arm of the person dragging it acts at 23 degrees to the horizontal, then what is the total tension in the person's arms? ...?
Generally the equation for Horizontal motion is mathematically given as
[tex]\sumFx=FtCos \theta\\\\\sumFx=ma[/tex]
Generally the equation for vertical motion is mathematically given as
[tex]Ftsin\theta+fn=mh\\\\Therefore\\\\Ft=\frac{7.5*9.8-23}{sin23}[/tex]
Ft=129N
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Find the limit of n*sin(pi/n). ...?
Which subatomic particles each have a positive electrical charge?
a. protons
b. neutrons
c. electrons
Answer: Option (a) is the correct answer.
Explanation:
Every atom consists of three sub-atomic particles which are protons, neutrons and electrons.
Inside the nucleus of an atom, there will be only protons and neutrons. Whereas electrons revolve around the nucleus of an atom.
Protons have a positive charge, neutrons have no charge and electrons have a negative charge.
Therefore, we can conclude that protons are the subatomic particles and each have a positive electrical charge.
Among subatomic particles, it's protons that have a positive charge. Neutrons are neutral and electrons have a negative charge.
Explanation:In terms of subatomic particles and their electrical charges, it's protons that carry a positive charge. Neutrons, as their name suggests, are neutral and do not have a charge, and electrons have a negative charge.
So, for the list provided, the subatomic particle having a positive electrical charge is the proton. This is a fundamental concept in Physics, especially in the realm of atomic structure and electricity.
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Which situations describe an elastic collision?
a. two glass marbles bounce off each other.
b. rodrick flops onto his sofa and sinks into the cushion.
c. a tossed water balloon flattens when it lands on the grass.
d. a bowling ball knocks over five pins.
Answer;
A. two glass marbles bounce off each other.
Explanation;
Elastic collisions are collisions in which both momentum and kinetic energy are conserved. The total system kinetic energy before the collision equals the total system kinetic energy after the collision. If total kinetic energy is not conserved, then the collision is referred to as an inelastic collision.
An elastic collision occurs when the two objects "bounce" apart when they collide. Two rubber balls are a good example. In an elastic collision, both momentum and kinetic energy are conserved. Almost no energy is lost to sound, heat, or deformation.
Final answer:
The situation that describes an elastic collision among the options given is two glass marbles bouncing off each other, as it aligns with the conservation of kinetic energy, which is characteristic of an elastic collision. Therefore, the correct option is a.
Explanation:
The question asks which situations describe an elastic collision. An elastic collision is characterized by the total kinetic energy of the objects involved being conserved post-collision. Among the given scenarios, two glass marbles bouncing off each other i.e. option a best exemplifies an elastic collision.
This is because, in theory, when two glass marbles collide, they do not lose any of their internal kinetic energy during the event, which is a hallmark of elastic collisions. This concept aligns with experiments that demonstrate the conservation of momentum and kinetic energy in collisions of hard objects with negligible energy loss through sound, heat, or deformation.
Other options, such as Rodrick flopping onto his sofa, a tossed water balloon flattening when it lands, and a bowling ball knocking over pins, describe scenarios where energy is not conserved in the same manner, indicating inelastic collisions. These cases involve significant energy transformation or absorption, such as into sound, heat, or deformation, which does not align with the properties of elastic collisions.
At a stoplight, a truck traveling at 15 m/s passes a car as it starts from rest. The truck travels at constant velocity and the car accelerates at 3 m/s^2. How much time does the car take to catch up to the truck?
Galileo was the first scientist to do which of the following?
Answer
Correct answer is define and measure the speed
Explanation
Galileo was the first scientist who define speed and give the formula of speed as distance over time
discover radioactivity
This option is also not correct because Radioactivity was discovered by Henri Becquerel in 1852.
invent the reflecting telescope
this option is not correct because reflecting telescope was discovered by Sir Isaac Newton in 1668
propose the heliocentric theory:
This option is also not correct because Nicolaus Copernicus proposed the
heliocentric theory in 1543
In which direction does a magnetic force act on an electron that is moving in the positive x-direction in a magnetic field pointing in the positive z-direction?
A) any direction in the xy-plane
B) the negative y-direction
c) the negative x-direction
D) the positive y-direction
a particle with charge q is at rest when a magnetic field is suddenly turned on. The field
points in the z-direction. What is the direction of the net force acting on the charged particle?
a) In the z-direction.
b) There is no force on the particle.
c) In the y direction
d) In the x direction
Final answer:
The magnetic force acts in the negative y-direction for an electron moving in the positive x-direction in a field in the positive z-direction. A charge at rest experiences no force in a magnetic field. So the correct option is B for the first question and the correct option is b for the second question.
Explanation:
The direction of the magnetic force on an electron moving in the positive x-direction in a magnetic field pointing in the positive z-direction, according to the right-hand rule and considering the negative charge of an electron, would be in the negative y-direction. This can be visualized by pointing the palm of your right hand in the direction of the electron's velocity (positive x-direction), the fingers in the direction of the magnetic field (positive z-direction), and then flipping the direction because the charge is negative, giving us the force in the negative y-direction.
As for a static charge in a magnetic field, no magnetic force is exerted on a particle with charge q that is at rest when a magnetic field is turned on. A magnetic force only acts on moving charges, therefore the particle will experience no force.
A firecracker shoots up from a hill 160 feet high with an initial speed of 90 feet per second. Using the formula H(t) = −16t2 + vt + s, approximately how long will it take the firecracker to hit the ground? ...?
Answer : t = 7.044 sec
Explanation :
It is given that,
Velocity, [tex]v=90\ feet/sec[/tex]
distance, [tex]s=160\ m[/tex]
[tex]H(t)=-16\ t^2+ vt+ s[/tex]
When firecracker hits the ground hen H(t) = 0
So, [tex]-16 t^2+90\ t+160=0[/tex]
or
[tex]8 t^2-45\ t-80=0[/tex]
Solving this quadratic equation, we get
[tex]t=\dfrac{-(-45) \pm \sqrt{(-45)^2-4(8)(-80)} }{2(8)}[/tex]
[tex]t=\dfrac{45\ \pm\sqrt{4585} }{16}[/tex]
[tex]t=7.044\ sec[/tex]
Neglecting negative values as time can't be negative.
Firecracker will take 7.044 sec to hit the ground.
Covalent bonds do what?
Share electrons
Take and give protons
Take and give electrons
Take voltrons but share megatrons