PHYSICS
MIDDLE SCHOOL

Answer: The NET force is the sum of all the forces that act upon each other.

Answer: the resultant force

COLLEGE

During an experiment, a toy car accelerates forward for a total time of 5 s. Which of the following procedures could a student use to determine the average net force exerted on the car during the 5 s that the car accelerates? a. Use a meterstick and stopwatch to measure the distance the car travels for the 5 s. b. Use a balance to determine the mass of the car. Use a motion sensor to measure the speed of the car at a time of 0 s and a time of 5 s.c. Use a balance to determine the mass of the car. Use a meterstick to measure the distance the car travels for the 5 s. d. Use a motion sensor to measure the speed of the car at a time of 0 s and a time of 5 s. Use a meterstick to determine the distance the car travels for 5 s.

Answer:

b)

Explanation:

According Newton's 2nd Law, the net force on an object (assuming we can consider it like a point mass), produces an acceleration on the mass of the object, expressed in this way:

Fnet = m*a (1)

By definition, the acceleration is the rate of change of velocity:

If we choose t₀ = 0, we can see that if we measure vf and v₀, as time is known, we can get the value of a.

Using a balance to determine the mass of the car, and replacing all the values in (1), we can get the magnitude of the net force exerted on the car during the 5 s that the car accelerates, as required.

Answer:

What speed is the car traveling at the longest distance and the shortest distance, and how do they compare?"

"Does the car move faster or slower for longer distances?"

COLLEGE

The first law of thermodynamics can be given as ________.

The first law of thermodynamics can be written as

where

is the variation of internal energy of the system

is the amount of heat absorbed by the system

is the work done by the system on the surrounding.

Using this form, the sign convention for Q and W becomes:

Q > 0 --> heat absorbed by the system (because it increases the internal energy)

Q < 0 --> heat released by the system (because it decreases the internal energy)

W > 0 --> work done by the system (for instance, an expansion: when the system expands, it does work on the surrounding, and so the internal energy decreases, this is why there is a negative sign in the formula Q-W)

W < 0 --> work done by the surrounding on the system (for instance, a compression: when the system is compressed, the surrounding is doing work on the system, and so the internal energy of the system increases)

where

is the variation of internal energy of the system

is the amount of heat absorbed by the system

is the work done by the system on the surrounding.

Using this form, the sign convention for Q and W becomes:

Q > 0 --> heat absorbed by the system (because it increases the internal energy)

Q < 0 --> heat released by the system (because it decreases the internal energy)

W > 0 --> work done by the system (for instance, an expansion: when the system expands, it does work on the surrounding, and so the internal energy decreases, this is why there is a negative sign in the formula Q-W)

W < 0 --> work done by the surrounding on the system (for instance, a compression: when the system is compressed, the surrounding is doing work on the system, and so the internal energy of the system increases)

COLLEGE

Some incandescent light bulbs are filled with argon gas. what is vrms (in m/s) for argon atoms near the filament, assuming their temperature is 2000 k?

The root mean square of the particles in a gas is given by

where

R is the gas constant

T is the absolute temperature of the gas

Mm is the molar mass of the gas

For the argon gas in our problem, the temperature is T=2000 K while the molar mass of argon is , so we can find the rms speed of the gas by using the previous formula:

where

R is the gas constant

T is the absolute temperature of the gas

Mm is the molar mass of the gas

For the argon gas in our problem, the temperature is T=2000 K while the molar mass of argon is , so we can find the rms speed of the gas by using the previous formula:

MIDDLE SCHOOL

The data and graph below were generated from a collision between Cart 1 (with mass 500 g) and Cart 2 (with mass 250 g) which occurred on a

level, frictionless track what is the total momentum

Answer:

The total momentum of the carts is p = 5000 g cm/s

Explanation:

Given data,

The mass of the cart 1, m₁ = 500 g

The mass of the cart 2, m₂ = 250 g

Let the velocity of the cart 1 be, v₁ = 5 cm/s

The velocity of the cart 2 be, v₂ = 10 cm/s

According to the law of conservation of momentum, then the total momentum of the carts before and after will be the same.

Therefore,

p = m₁v₁ + m₂v₂

= 500 x 5 + 250 x 10

= 5000 g cm/s

Hence, the total momentum of the carts is p = 5000 g cm/s