12. A squirrel standing on a branch rolls an acorn toward a hole in the tree. To determine how the potential energy of the acorn changes in relation to the earth, the position of what two objects must be considered?

A) The position of the squirrel on the branch and the earth
B) The height of the branch and the position of the acorn
C) The position of the acorn and the earth
D) The position of the acorn and the width of the hole in the tree

13. Ellen drops a ball from a cliff. Which statement best describes the ball's energy as it falls from her hand?
A) The ball's kinetic energy decreases while its potential energy increases.
B) The ball's kinetic energy increases but its potential energy remains the same.
C) The ball's potential energy decreases while its kinetic energy increases.
D) The ball's potential energy is changed to thermal energy.

15. Mrs. Wilson is driving her car to the store. She drives on a street where the speed limit is 50 mph. Then she turns onto a street where the speed limit is 45 mph. What happens to the kinetic energy of her car?
A) When she slows from 50 mph to 45 mph, the car’s kinetic energy stays the same.
B) When she speeds up from 45 mph to 50 mph, the car’s kinetic energy is changed to potential energy.
C) When she slows from 45 mph to 50 mph, the car’s kinetic energy decreases.
D) When she slows from 50 mph to 45 mph, the car’s kinetic energy increases

1 answer

Here are the answers to your questions:

12. To determine how the potential energy of the acorn changes in relation to the earth, the position of what two objects must be considered?

C) The position of the acorn and the earth
This is correct because potential energy is dependent on the height of the object above a reference point, which is usually the ground or Earth.

13. Ellen drops a ball from a cliff. Which statement best describes the ball's energy as it falls from her hand?

C) The ball's potential energy decreases while its kinetic energy increases.
This is correct because as the ball falls, it loses potential energy (due to the decrease in height) and gains kinetic energy (due to the increase in speed).

15. Mrs. Wilson is driving her car to the store. She drives on a street where the speed limit is 50 mph. Then she turns onto a street where the speed limit is 45 mph. What happens to the kinetic energy of her car?

C) When she slows from 50 mph to 45 mph, the car’s kinetic energy decreases.
This is correct as kinetic energy is proportional to the square of the speed. Reducing speed from 50 mph to 45 mph results in a decrease in kinetic energy.