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.

16. Which object has kinetic energy?

a
a bird perched in a tree
b
a person standing at the top of stairs
c
a ball sitting under a table
d
a person running on the sidewalk

17. Which object has potential energy?

a
a person walking down the street
b
a soccer ball rolling across a field
c
a car moving down the interstate
d
an acorn sitting on top of a roof

1 answer

Here are the answers to your questions:

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? C) The position of the acorn and the earth
The potential energy of an object is generally calculated with reference to a specific point, typically the ground or the earth. Thus, the position of the acorn and the earth must be considered.

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.
As the ball falls, it loses potential energy (due to a decrease in height) and gains kinetic energy (as its speed increases).

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.
Kinetic energy is dependent on the square of the speed, so if she decreases her speed, her kinetic energy decreases.

16. Which object has kinetic energy? d) a person running on the sidewalk
Kinetic energy is the energy of motion, so a person running (in motion) possesses kinetic energy.

17. Which object has potential energy? d) an acorn sitting on top of a roof
Potential energy is stored energy based on position. An acorn sitting on top of a roof has gravitational potential energy relative to the ground below.