## Review Questions

1. Which has more inertia, a 6-kg bowling ball sitting on the floor or one rolling down the lane? Why?

2. What are the two ways to express Newton's second law?

3. When might it be advantageous for a person to increase the inertia used in a movement?

4. Do smaller or larger muscle angles of pull on a distal segment tend to create more joint rotation? Why?

5. What are strategies to increase the friction between a subject's feet and the floor?

6. What two things can be changed to increase the impulse applied to an object? What kinds of human movement favor one over the other?

7. If the force from the tibia on the femur illustrated below was 1000 N acting at 30° to the femur, what are the longitudinal

(causing knee compression) and normal (knee shear) components of this force? Hint: move one component to form a right triangle and solve.

8. Give human movement examples of the three mechanical energies.

9. Compare and contrast muscular strength and muscular power.

10. How is momentum different from kinetic energy?

11. A rock climber weighing 800 N has fallen and is about to be belayed (caught with a safety rope) by a 1500-N vertical force. Ignoring the weight of the rope and safety harness, what is the vertical acceleration of the climber? Hint: remember to sum forces with correct signs (related to direction).

12. Draw a free-body diagram of a proximal segment of the body showing all forces from adjacent segments. Draw a free body diagram of an adjacent segment using Newton's third law to determine the size and direction at the joint.

13. What are the potential kinetic mechanisms that make a sequential motion of segments in high-speed movements the optimal coordination?

14. Do the angles of pull (relative to the body) of free weights change during an exercises? Why?

15. An Olympic lifter exerts a 4000-N upward (vertical) force to a 30-kg barbell. What direction will the bar tend to move, and what is its vertical acceleration?

## 100 Bowling Tips

Playing bowling with your friends can help you decide if it is indeed the hobby that you want to invest your time on today. Aside from that, it can help you get a better feel of the sport. More importantly, when you play with your friends, it would become a more fun activity, which you can look forward to each week.

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