AP Physics B : AP Physics B
Study concepts, example questions & explanations for AP Physics B
All AP Physics B Resources
Example Questions
Example Question #11 : Electricity And Magnetism
Which of the following changes to a copper wire will lead to the greatest decrease in voltage?
Increasing the length of the copper wire by a factor of two
Increasing the current through the copper wire by a factor of two
Increasing the cross-sectional area of the copper wire by a factor of two
Replacing the copper wire with a more conductive material
Increasing the cross-sectional area of the copper wire by a factor of two
According to Ohm’s law a decrease in current and/or resistance will lead to a decrease in voltage, since voltage is directly proportional to both current and resistance.
Increasing the current will not decrease voltage. Remember that resistance is defined as:
In this formula, 
The only answer that will lead to a decrease in voltage is the choice to increase the cross-sectional area of the wire.
Replacing the copper wire with a more conductive material will increase the resistivity, which will subsequently increase resistance and voltage.
Example Question #2 : Electric Circuits
A student assembles a circuit made up of a voltage source and two resistors. All three circuit elements are connected in parallel. The voltage across the voltage source is 
The current through the 
The voltage across the 
The voltage across the 
The current through the 
The voltage across the
When circuit elements, such as resistors, are connected in parallel they will have the same voltage drop. The current through the 
Since voltage is the same across resistors, the lower resistance (
Example Question #31 : Ap Physics 1
The moon's distance from the center of the Earth was decreased by a multiple of three. How would this affect the gravitational force of the Earth on the moon?
The gravitational force would not be affected, because the moon's mass is the same
It would increase by a factor of three
It would increase by a factor of nine
It would decrease by a factor of nine
It would increase by a factor of nine
The law of gravitation is written as 
Since the radius of the two masses acting on each other is squared, and is found in the denominator, a decrease in the radius by a multiple of three will cause a nine-fold increase in the gravitational force.
Example Question #2 : Newton's Second Law
What is the acceleration due to gravity on a planet on which an object with a mass of 20.0kg has a weight of 270N?
0.074m/s2
13.5m/s2
10m/s 2
27m/s2
13.5m/s2
Solve the following equation for acceleration, using the values given in the question.
Example Question #2 : Motion In One Dimension
A ball is thrown horizontally off a cliff of height of 
First we will find the time required for the ball to reach the ground. Since the ball is thrown horizontally, it has no initial vertical component. We use the following equation to solve for the total flight time:
We are given the change in height, initial velocity, and acceleration. Using these values, we can solve for the time. Note that the change in height will be negative, since the ball is traveling downward.
Finally, we use the horizontal velocity to find the distance traveled in 
Example Question #91 : Ap Physics B
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.
Certified Tutor
Certified Tutor
All AP Physics B Resources
