A 900-N lawn roller is to be pulled over a 5-cm (high) curb. Radius of roller is 25 cm. What minimum pulling force is needed if angle made by handle is (a) 0 deg (b) 30 degrees?

Gauss law states that the electric flux through any closed surface is proportional to the net electric charge inside the surface. This is expressed mathematically in the form of:

Φ = Q / εo

Where,

Φ = the electric flux = unknown (which we have to find for)

Q = the net electric charge = 5.0 µC = 5 E-6 C

εo = the permittivity of free space = a constant value = 8.85 E-12 C^2 / N m^2

Plugging in the values into the equation will result in:

Φ = 5 E-6 C / (8.85 E-12 C^2 / N m^2)

Φ = 564,971.75 Wb = 5.6 x 10^5 Wb 

The energy of one photon of light with a wavelength of 445 nm can be calculated using Planck's equation, E = hv. This requires converting the wavelength to frequency using c = wavelength times frequency, and then substituting the frequency back into Planck's equation. The energy of one photon of 445 nm blue light is approximately 4.47 x 10^-19 Joules.

To determine the energy of one photon of light with a wavelength of 445 nm (visible light electromagnetic radiation), we can use Planck's equation, which states E = hv (energy equals Planck's constant times frequency). However, we must first convert wavelength to frequency via the speed of light equation (c = wavelength times frequency). After getting the frequency, we can substitute it back into the Planck's equation.

By doing these calculations, we find:

Therefore, one photon of 445 nm blue light has an energy approximately equal to 4.47 x 10^-19 Joules.

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The average velocity can be calculated using the formula:

v = d / t

For the 1st car, the velocity is calculated as:

v1 = 8.60 m / 1.80 s = 4.78 m / s

While that of the 2nd car is:

v2 = 8.60 m / 1.66 s = 5.18 m / s

Now we can solve for the acceleration using the formula:

v2^2 = v1^2 + 2 a d

Rewriting in terms of a:

a = (v2^2 – v1^2) / 2 d

a = (5.18^2 – 4.78^2) / (2 * 8.6)

a = 0.23 m/s

Therefore the train has a constant acceleration of about 0.23 meters per second.

The density of the concrete is approximately 0.965 g/cm³. The result does not support the statement that rebar is mostly iron.

The density of a substance can be calculated by dividing its mass by its volume. In this case, the mass of the concrete is 43.8 grams and the volume is calculated by multiplying the length, width, and height, which is 3.7 cm x 2.1 cm x 5.8 cm = 45.4014 cm³ (rounded to the nearest 0.0001 cm³). Therefore, the density of the concrete is 43.8 g / 45.4014 cm³ ≈ 0.965 g/cm³.

(b) Since the density of the concrete in (a) is less than the density of iron (approximately 7.87 g/cm³), the result does not support the statement that rebar is mostly iron.

Answer:

The third answer is correct:)

Explanation:

Final answer:

During the electrolysis of molten potassium bromide, the half-reaction that occurs at the cathode is the reduction of potassium ions (K+) to form potassium metal (K).

Explanation:

The half-reaction that occurs at the cathode during the electrolysis of molten potassium bromide is the reduction of potassium ions (K+) to form potassium metal (K).

The half-reaction can be represented as:

2K+ + 2e- -> 2K

At the cathode, positive ions are reduced and gain electrons to form neutral atoms or molecules.

Answer:

B. Certified

Explanation: I agree with the other person and i also believe it is correct

<<<<<<<<<< B is the answer >>>>>>>

The angular speed of the minute hand of a watch is calculated by dividing the total angle of rotation (2π rad) by the period of rotation (3600 s), which equals 0.1047 rad/min. This indicates the degree of the minute hand's rotation per minute. The right-hand rule also designates the angular velocity's direction.

The angular speed of the minute hand of a watch refers to the degree of rotation of the minute hand per unit of time. In the particular case of a watch, the minute hand completes one full revolution (360° or 2π rad) in one hour (60 minutes or 3600 seconds). Therefore, the angular speed ω can be calculated as the total angle of rotation (2π rad) divided by the period of rotation, which is 3600 seconds.

Thus, the angular speed is calculated as ω = 2π rad/3600 s. By converting this to radian per minute, which is a more typical unit for a watch, we obtain that the angular speed of the minute hand of a watch is 0.1047 rad/min. This means that in each minute, the minute hand rotates 0.1047 radians.

This concept and calculation is part of what's studied in rotational motion in physics, where the right-hand rule can also be used to determine the direction of the angular velocity vector.

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Answer:

0.50 s

Explanation:

you're welcome

By dividing the temperature by two and adding 30 to the result, you can convert a temperature in Celsius to Fahrenheit. You will receive a rough temperature in Fahrenheit from this.

For more accurate temperature measurements, use Fahrenheit. Additionally, it is preferable since people are more concerned about air temperature than water temperature.

Because of these factors, we ought to embrace Fahrenheit as a unit of temperature measurement rather than reject it in favor of its metric equivalent.

Fahrenheit and Celsius temperature scales are seen on the majority of thermometers. Read the °F figures (degrees of Fahrenheit).

Therefore, To get a more accurate approximation, multiply the temperature by 2, take out 10%, and then add 32 to the result.

Learn more about thermometer here:

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Answer:

Applied force, weight, normal force and frictional force

Explanation:

Bob is pushing a lawn mower up a hill with the mower tilting slightly to the right. We have to write the forces acting on the mower.

The following are the forces that are acting on the mower.

1. Applied force - The force with which Bob is pushing a lawn.

2. Weight - Its weight is equal to, W = m g

3. Normal force - that balances its weight

4. Frictional force - It always opposes the motion of the mower.

Hence, this is the required solution.

The lawn mower is acted upon by four different forces.

Vector quantities are those quantities that posses both magnitude and direction. Force is a vector quantity. Hence, the resultant force acting on a lawn mover can be obtained as the resultant of the four forces that act on the mower.

The four forces that act on the lawn mower are;

Hence, the lawn mower is acted upon by four different forces.

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Final answer:

To find the acceleration of a moving object after 5 seconds, given the distance function 2t/(4 + t), we first find the velocity by differentiating the distance function, then find the acceleration by differentiating the velocity. The acceleration after 5 seconds is approximately -0.022 m/[tex]s^2[/tex].

Explanation:

The question involves finding the acceleration of a moving object after 5 seconds, given that the distance it has traveled after t seconds is represented by the function 2t/(4 + t). To find the acceleration, we first need to determine the velocity function by differentiating the distance function with respect to t, and then find the acceleration by differentiating the velocity function with respect to t again.

The velocity v(t) is the first derivative of the distance function s(t) = 2t/(4 + t). Using the quotient rule for differentiation, v(t) = d/dt [2t/(4 + t)]. Calculating the derivative gives us v(t) = 8/(4 + t)^2.

The acceleration a(t) is the derivative of the velocity function. So, a(t) = d/dt [8/(4 + t)^2]. Differentiating this gives a(t) = -16/(4 + t)^3.

Plugging t = 5 into the acceleration function, a(5) = -16/(4 + 5)^3 = -16/729. Therefore, the acceleration of the object after 5 seconds is approximately -0.022 m/[tex]s^{2}[/tex], rounding to three decimal places.

The work done when lifting a 185 g tomato by 17.9 m is approximately 32.5 joules, calculated using the weight of the tomato as the force and the distance it is lifted.

To calculate the work done when lifting an object, we can use the formula Work (W) = Force (F) × Distance (D) × cos(θ), where θ is the angle between the force and the displacement. In the case of lifting an object vertically, the angle is 0°, so the cosine term is 1, and the equation simplifies to W = F × D. For a 185 g tomato lifted 17.9 m, we first need to convert the mass of the tomato to kilograms by dividing by 1000, which gives us 0.185 kg. The force is equal to the weight of the tomato, which is the mass (m) multiplied by the acceleration due to gravity (g = 9.8 m/s²), F = m × g. Thus, the force is F = 0.185 kg × 9.8 m/s² = 1.813 N. The work done is then W = 1.813 N × 17.9 m = 32.463 J, which we round to 32.5 J when expressing it with three significant figures.

Answer:

greater than

Explanation:

When looking at nuclear masses, the mass of the parts is always greater than the mass of the whole.

Example with helium:

The atomic number of helium is 2, which means that it has two protons in its nucleus. The most common isotope of helium, ^4He, has two neutrons in addition to the two protons, giving it a mass number of 4. The mass of a proton is about 1.0073 atomic mass units (amu), and the mass of a neutron is about 1.0087 amu. Therefore, the total mass of the four nucleons (two protons and two neutrons) in the ^4He nucleus is:

2 protons x 1.0073 amu/proton + 2 neutrons x 1.0087 amu/neutron = 4.0314 amu

However, the actual (whole) mass of ^4He nucleus is found to be slightly less than the sum of the parts of the masses of its constituent nucleons. This means that the mass of the parts is always greater than the mass of the whole.

Answer:

Time period

Explanation:

The time taken by a wave to complete one cycle is called the time period of a wave. It is denoted by T. The number of vibration per second is called the frequency of the wave.

The relation between the time period and the frequency is inverse i.e.

[tex]T=\dfrac{1}{\nu}[/tex]

If the number of vibrations increases its time period will decrease.

Similarly, for a simple pendulum the time period to complete one cycle is :

[tex]T=2\pi\sqrt{\dfrac{l}{g}}[/tex]

l and g are length of pendulum and acceleration due to gravity.