1. Unit 2 Forces in Motion Answers with Explanations
Q1. C Right before it hits the ground. Kinetic energy is the energy of motion. The faster an object moves the more kinetic energy it has. The object is moving fastest just before it hits the ground.

2. Q2. A more velocity in less time. +acceleration is speeding up,
acceleration is slowing down
A steeper graph has greater acceleration

3. Q3 C. Gravity Gravity is the force that pulls thrown objects towards Earth

4. Q4. C. Speed and direction

5. Q5. D An object at rest will remain at rest unless acted upon by an outside force. Newton’s 1st Law (Law of Inertia)

6. Q6. Your mass is the same and you weigh less on the moon
Q6. Your mass is the same and you weigh less on the moon. The moon has a smaller mass and therefore a weaker force of gravity which decreases your weight.

7. Q8. C the motion of the desk does not change
Q8. C the motion of the desk does not change. Balanced forces result in no change in motion.

8. Q9. B The earth has more mass than the desk

9. Q10. C Velocity includes direction and speed does not.

10. Q11 C. Truck #1 is pulling with a greater force to the left.
An object will move in motion in the direction of the greatest force.
The forces are unbalanced.

11. Q12. D There is not an unbalanced force acting on the object
Q12. D There is not an unbalanced force acting on the object. Newton’s 1st Law.

12. Q13. B Student #1 will accelerate their cart faster than student #1 Newton’s 2nd Law Acceleration = force / mass

13. Q14. C. Ice skating rink The smoothest surface has the least friction i.e. ice has less friction than concrete Friction slows the motion of objects

14. Q15. B The total amount of energy stays the same
Q15. B The total amount of energy stays the same. Law of Conservation of energy Energy is not created or destroyed it just changes form. You should have the same amount at the beginning and the end.

15. Q16 B. The gravitational force between two objects is increasing
Q16 B. The gravitational force between two objects is increasing. The strength of gravity depends on two things. Increased mass = stronger gravity force. Decrease in distance = stronger gravity force.

16. Q 17. C. The object is moving at a constant speed.

17. Q 18 D. all of the above.
Acceleration, deceleration and changing distance.
Velocity is changing over time.

18. 19. C. Friction