AP Physics 1 : Forces
Study concepts, example questions & explanations for AP Physics 1
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Example Questions
Example Question #591 : Newtonian Mechanics
What is the mass of 
Weight is the force that gravity exerts on an object. Weight is determined using the equation
Where 
Given the weight of an object and the gravitational constant acting on it, we find the mass using
Example Question #31 : Forces
If a person has a mass of 
Weight is the force that gravity exerts on an object. Weight is determined using the equation
Where
The mass of an object is independent of gravity, therefore it does not change from planet to planet. The mass of the person on Jupiter is 
On Jupiter, 
Example Question #31 : Forces
A shield has a mass of 
Weight is the force that gravity exerts on an object. Weight is determined using the equation
Where
The mass of an object is independent of gravity, therefore it does not change from planet to planet. The mass of the shield on the moon is 
On the moon, 
Example Question #32 : Specific Forces
Suppose that a person standing in an elevator suddenly accelerates upward to go to the next floor. If the elevator accelerates upward by an amount 
The person's weight will decrease by a factor of
The person's weight will increase by a factor of
There person's weight will decrease by a factor of
There person's weight will increase by a factor of
There person's weight will remain the same
The person's weight will increase by a factor of
For this question, we're told that a person is accelerating upward while in an elevator, and we're asked to find how this person's weight changes as a result.
To begin, it's most useful to solve this problem by considering the forces acting in the vertical direction. Downward, we have the mass of the person. Upward, we have the tension in the cord that is pulling the elevator up. We can use this information to set up the following expression.
Also, note that the tension in the elevator is what is providing all the upward force. Thus, the elevator floor will be exerting this same amount of force on the person (normal force) and, as a result, the person will exert the same force (weight) on the elevator floor. Hence, tension is a measurement of the person's weight.
Now, we'll need to take the ratio of the person's weight while accelerating in the elevator to the person's weight while at rest. This will give us the factor by which his weight changes.
Example Question #31 : Specific Forces
A girl is standing on two feet on the ground. She then lifts her right foot in the air. How does this change the normal force affecting her?
None of these
It will be quadrupled
It will be doubled
It will be cut in half
No change
No change
Normal force is independent of surface area, and only dependent on the opposite force being applied, in this case gravity. While the pressure on her foot may change, the force of gravity pushing her down stays the same.
Example Question #32 : Forces
A 
The ground exerts an equal force as the person exerts on it, which is the normal force. This is simply the mass of the person times the acceleration due to gravity which is 
Example Question #33 : Forces
A 
This question tests your understanding of the concept of normal force. In a block that remains stationary, in which the only two forces acting upon it are the force of gravity, and normal force, you therefore know that the normal force must be equal to the force of gravity, since the block is not accelerating or decelerating (i.e. the sum of the forces is equal to zero).
Thus, we can set the normal force equal to the force of gravity, and solve as follows:
Therefore, the normal force exerted on the block by the ground is 
Example Question #1 : Universal Gravitation
A certain planet has three times the radius of Earth and nine times the mass. How does the acceleration of gravity at the surface of this planet (ag) compare to the acceleration at the surface of Earth (g)?
The acceleration of gravity is given by the equation 
For Earth, 
For the new planet,
So, the acceleration is the same in both cases.
Example Question #31 : Forces
A new planet is discovered with mass 
The equation to calculate the escape velocity from a planet is
The diameter of the planet is given and can be divided by two to determine the radius of the planet. By plugging in the given values, the escape velocity threshold can be determined:
Example Question #1 : Universal Gravitation
There are two isolated stars orbiting each other. The first star has a mass of 
None of the other answers
We need to know Newton's law of universal gravitation to solve this problem:
It is important to note that both suns will feel the same gravitational force. However, since they have different masses, they will accelerate at different rates.
Plugging in the variables we have, we get:
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