Viteza de aterizare a unui avion este de 45 m/s iar timpul deplasarii pe pista aerodromului este egal cu 30 s

Answer:  10.3

Explanation:  Edge

Statement a and e are in static equilibrium, b and d are in dynamic equilibrium and c is not at equilibrium at all.

When the net force acting on an object is zero, the object is said to be at equilibrium. The state of equilibrium can be classified into two: static and dynamic.

Static equilibrium is when the net force is zero resulting in the object being at rest or not moving.

Dynamic equilibrium is when the resultant force acting on an object is zero and the object is moving in a uniform motion (i.e. constant or unchanging speed).

A. a 200 pound barbell is held above your head

Since the barbel is "held above your head" and is implied to be at rest since there is no change in its position during the time it is held, then this situation is an example of static equilibrium.

B. A girder is being lifted at a constant speed by a crane

This is dynamic equilibrium because the object is moving "at a constant speed".

C. A girder is being lowered into place. It is slowing down.

This is not equilibrium condition because the objects is neither at rest nor moving at a constant speed. It is "slowing down", so the speed is decreasing.

D. A jet plane has reached its cruising speed and altitude.

The "cruising speed" is the speed that is maintained while the jet plane is traveling because this is considered to be the most efficient speed. Since it is maintained, the jet plane is said to be in constant motion. Therefore, this is dynamic equilibrium.

E. A box in the back of a truck doesn't slide as the truck stops.

This is static equilibrium because the box is stationary or not moving.

Keywords: equilibrium, static equilibrium, dynamic equilibrium

Objects in static equilibrium are at rest with balanced forces, while those in dynamic equilibrium move with constant velocity and no acceleration. A barbell held still is in static equilibrium, a girder moving consistently while being lifted is in dynamic equilibrium, and a plane at cruising altitude and speed is also in dynamic equilibrium.

Objects can be in either static equilibrium, dynamic equilibrium, or not in equilibrium at all. When an object is at rest and the net external force and torque acting on it are zero, it is in static equilibrium. On the other hand, an object in motion with constant velocity and zero acceleration, where the net external forces and torques are also zero, is in dynamic equilibrium.

The resistance of a lamp connected to a 12v battery that generates a current of 2.0A is calculated using Ohm's law to be 6 ohms.

The question asks about the resistance of a lamp connected to a 12v battery that generates a current of 2.0 A.

Using Ohm's law which states that voltage(V) equals current(I) times resistance(R), or V = IR , we can calculate the resistance. In this case, we know the current (I) is 2.0 A and the voltage (V) is 12 V.

We rearrange the formula to find R (resistance) = V/I. Substituting the given values, we have: R = 12v/2.0A = 6 ohms.

Hence, the resistance of the lamp at the current of 2.0 A is 6 ohms.

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Answer:

Both scientific law and theory are the scientific statements related to any natural phenomenon.

Both are the proved hypothesis but they differ as a scientific law tells how a natural phenomenon takes place whereas a theory explains why the natural phenomenon takes place.

A scientific law cannot be changed but a theory can be modified and changed when new evidence comes into existence.

Thus, both are different.

The density of the block is 8.9 gm/cm³

What is volume ?

Volume is a three dimensional space occupy by the body of particular shape. Generally expressed in cubic meter.

Here, it is given that length of block (l) = 2 cm

breadth of block (b) = 4 cm

heigth of block (h) = 5 cm

weight of block (m) = 356 gm

the volume of the block is calculated using formula :

[tex]\begin{aligned}V&= lbh\\&=2\cdot4\cdot5\\&=40 \text{ cm}^{3}\end{aligned}[/tex]

Now density of block will  be :

[tex]\begin{aligned}\rho&=\frac{m}{V}\\&=\frac{356}{40}\\&=8.9 \:\text{gm}/ \text{cm}^{3}\end{aligned}[/tex]

Therefore, the density of the block is 8.9 gm/cm³

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Answer: Option (b) is the correct answer.

Explanation:

A positively charged particle that consists of two protons and two neutrons is known as an alpha particle.

The symbol for alpha particle is [tex]^{4}_{2}\alpha[/tex]. An alpha particle is similar to a helium atom because helium atom also has mass number (number of protons + number of neutrons) as 4 and atomic number (number of protons) as 2.

Symbol of helium atom is [tex]^{4}_{2}He[/tex].

Thus, we can conclude that an alpha particle is also referred to as a nucleus of helium isotope.

Answer:

26m/s

Explanation:

Acceleration is the change in velocity of a body with respect to time. Mathematically,

Acceleration = change in velocity/time

Acceleration = final velocity (v) - initial velocity (u)/time (t)

Given a = 4m/s², v = ? u = 18m/s, t = 2seconds.

Substituting in the given formula,

4 = v-18/2

8 = v-18

v = 8+18

v = 26m/s

The new velocity of the body is therefore 26m/s

Answer:

[tex]6.3\times10^3 km[/tex]

Explanation:

First, convert meters to kilometers:

[tex]6370000m*\frac{1km}{1000m} =6370km[/tex]

Now, express it using scientific notation following the next steps:

Therefore:

[tex]6370km=6.3\times 10^3km[/tex]

The radius of the Earth in scientific notation with the correct number of significant digits is 6.37 × [tex]10^6[/tex] km

To express the radius of the Earth in scientific notation with the correct number of significant digits, we need to count the number of significant digits in the original measurement and then convert it to scientific notation.

The original measurement is 6,370,000 meters.

Step 1: Count the significant digits:

There are four significant digits in the number 6,370,000.

Step 2: Convert to scientific notation:

To express the number in scientific notation, we move the decimal point to the position where we have only one non-zero digit before the decimal point. In this case, that's the number 6. To do that, we need to move the decimal point six places to the left:

6,370,000 = 6.37  × [tex]10^6[/tex]

Step 3: Add the correct number of significant digits:

Since there were four significant digits in the original number, we need to keep four significant digits in the scientific notation as well.

Therefore, the radius of the Earth in scientific notation with the correct number of significant digits is:

6.37  × [tex]10^6[/tex] km

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Final answer:

The round trip swimming in the river with a current takes a total of 2016.8 seconds, while the same trip in still water would take 1666.7 seconds. The additional time required when there is a current is because the effective speed of the swimmer is reduced when going against the current, which outweighs the time saved by the increased speed when going with the current.

Explanation:

A river has a steady speed of 0.500 m/s and a student swims upstream a distance of 1.00 km and swims back to the starting point. Given these conditions, we can calculate the time taken for the entire trip, the time required for a similar trip in still water, and understand why swimming in a current takes longer.

Part A: Time for the round trip with current

Upstream, the student's effective speed is 0.70 m/s (1.20 m/s - 0.500 m/s) since the current opposes the swimmer. Downstream, the effective speed is 1.70 m/s (1.20 m/s + 0.500 m/s) as the current aids the swimmer. To find the time, we use the formula time = distance / speed. Thus, the time taken upstream is 1428.6 seconds and downstream is 588.2 seconds. The total time for the round trip is 2016.8 seconds.

Part B: Time for the same swim in still water

In still water, where there is no current, the speed of the swimmer is 1.20 m/s. The total distance of 2.00 km (1.00 km upstream and 1.00 km downstream) would require 1666.7 seconds to swim, calculated using the same distance/speed formula.

Part C: Intuition behind increased time with current

Intuitively, when there is a current, the effective speed of the swimmer decreases when swimming upstream because the current opposes the swimmer's motion, and although it increases when swimming downstream, the overall effect is that more time is needed to complete the swim as compared to swimming in still water. This is due to the fact that the loss of speed when going against the current has a more significant impact on the total time than the gain in speed when going with the current.

Acceleration due to gravity = 2.6m/s²

Length of building = d = 88.3m

Time he needed before she hits the ground = ?
 we can find the time by using the formula;

D = 1/2at²

Now putting the value;

88.3 = (1/2) a t²

88.3 = 1/2 x 23.6 x t²

t² = 88.3 / 11.8

= 7.48

Answer:

Duck's kinetic energy is 64.8 Joules

Explanation:

It is given that,

Mass of the duck, m = 0.9 kg

Velocity of the duck is, v = 12 m/s

We have to find the velocity of the duck. It is given due to the motion of an object. Mathematically, it is written as :

[tex]KE=\dfrac{1}{2}mv^2[/tex]

[tex]KE=\dfrac{1}{2}\times 0.9\ kg\times (12\ m/s)^2[/tex]

KE = 64.8 Joules

Hence, the kinetic energy of the duck is 64.8 Joules              

You will take 400N divide by 2. The answer will be 200N.

Explanation :

Given that,

Mass of the spaceship 1, m = 300 kg

Initial momentum of the spaceship 1, p = 600 kgm/s

Momentum is the product of the mass and the velocity with which it is moving i.e.

p = m v

[tex]v=\dfrac{p}{m}[/tex]

[tex]v=\dfrac{600\ kgm/s}{300\ kg}[/tex]

[tex]v=2\ m/s[/tex]

The initial velocity of the spaceship 1 is 2 m/s.

Hence, this is the required solution.

Final answer:

To find the initial speed of spaceship 1 with a momentum of 600 kg-m/s and mass of 300 kg, one should use the momentum formula (momentum = mass * velocity) and solve for velocity, resulting in an initial speed of 2 m/s.

Explanation:

To calculate the initial speed of spaceship 1 with a given momentum, we need the formula for momentum, which is the product of mass and velocity (p = m * v). Since we have the mass (m = 300 kg) and the momentum (p = 600 kg-m/s), we can solve for the initial speed (v) of spaceship 1 by rearranging the formula to v = p / m.

Doing the calculation gives us v = 600 kg-m/s / 300 kg, which results in v = 2 m/s. Therefore, the initial speed of spaceship 1 is 2 meters per second.

The required answers are: 1) Object C, 2) Object B, 3) Object C.

Based on the graphs, here are the answers to the given questions:

Object C had a reta rding force acting on it. This is because its speed is decreasing over time, which means it is decelerating.

Object B was not accelerating. This is because its speed is constant over time.

Object C traveled the greatest distance in the 3.0-second time interval. The area under the speed-time curve represents the distance traveled, and Object C's curve has the largest enclosed area.

Area = Triangle + rectangle

A = 1/2 x base x height + length x breadth

A = 1/2 x 3 x (30-20) + 3 x 20

A = 15 + 60

A = 75 = distance in meters.

Complete Question:

Based your answers to questions on the following four graphs, which represent the relationship between speed and time for four different objects, A, B, C, and D moving, in ạ straight line.

1. Which object had a reta rding force acting on it?

2. Which object was not accelerating?

3. Which object traveled the greatest distance in the 3.0-second time interval?                                

The query involves the application of physics specifically taking into consideration projectile motion. The minimum speed of the ball when it left the bat, assuming a 45° launch angle and no air resistance, is calculated to be approximately 28.36 m/s.

This is a question about projectile motion in physics and requires the understanding and application of kinematic equations. Projectile motion assumes air resistance is negligible, and the only force operating on the object is gravity.

The formula to calculate the initial velocity (or speed when the angle is 45°) of the projectile is v = sqrt((g * d) / sin(2θ)), where g is the acceleration due to gravity (approx. 9.8 m/s²), d is the distance, and θ is the launch angle.

So plugging in the values: sqrt((9.8 m/s² * 81 m) / sin(90°)) gives us approximately 28.36 m/s. Therefore, the minimum speed of the ball when it left the bat, assuming a 45° launch angle, is roughly 28.36 m/s.

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The torque exerted by the mouse's weight on the clock's minute hand is calculated to be 0.09163 N·m using the torque formula with force, radius, and the angle between them.

To determine the torque exerted by the mouse's weight on the clock's minute hand when it is 10 minutes past the hour, we need to apply the formula:

Torque (τ) = r × F × sin(θ)

Here:

Substituting these values into the formula:

τ = 0.17 m × 0.539 N × 1 = 0.09163 N·m.

Thus, the torque exerted by the mouse's weight about the rotation axis of the clock hand is 0.09163 N·m.

The answer is not B.

The density of gold is 19.3 grams per cubic centimeter. To convert this to metric tons per cubic meter, we convert grams to metric tons and cubic centimeters to cubic meters, which gives us a density of 19.3 metric tons per cubic meter.

The question asks for the density of gold in metric tons per cubic meter. Gold's known density is 19.3 grams per cubic centimeter. To convert this to metric tons per cubic meter, we first need to convert grams to metric tons. We know that 1 metric ton equals 1,000,000 grams. Therefore, 19.3 grams is 0.0000193 metric tons. Then, we need to convert cubic centimeters to cubic meters. As there are 1,000,000 cubic centimeters in a cubic meter, the density of gold becomes: 0.0000193 metric tons times 1,000,000, equaling 19.3 metric tons per cubic meter.

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The three hallmarks of science are empiricism, skepticism, and the use of rational arguments.

The three hallmarks of science are: empiricism, skepticism, and the use of rational arguments. Empiricism refers to the concept that all knowledge is derived from sensory experience. It involves the collection of data and observation of phenomena. Skepticism in science refers to the practice of questioning the validity and reliability of claims and not accepting them blindly. It involves requiring substantial evidence before affirming a claim. Rational arguments refer to using logical reasoning to explain natural events. Scientists use rational arguments to construct theories from experimental results.

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