Question

1. circle the letter of each sentence that is true about impulse and momentum.

a. when jumping from an elevated position down to the ground, you should keep your legs stiff to decrease the momentum.
b. a wrestler thrown to the floor should extend his time hitting the mat by relaxing his muscles and spreading the impulse to his foot, knee, hip, ribs, and shoulder.
c. when a boxer gets punched, she should move her head away from the punch to increase the contact time and reduce the force.
d. a dropped dish is more likely to survive a fall on carpet rather than concrete, because the softness of the carpet leads to increased contact time.

Explanation:

• a. False. Keeping legs stiff on landing increases the force of impact, not decrease momentum properly. The correct way is to bend legs to increase time of impact and reduce force.
• b. True. Relaxing muscles and spreading the impulse over different body - parts extends the time of hitting the mat, reducing the force.
• c. True. Moving the head away from a punch increases the contact time between the punch and the head, reducing the force of the impact according to the impulse - momentum theorem ($J = F\Delta t=\Delta p$).
• d. True. The softness of the carpet increases the contact time when the dish lands, reducing the force exerted on the dish, making it more likely to survive the fall.

Answer:

b. A wrestler thrown to the floor should extend his time hitting the mat by relaxing his muscles and spreading the impulse to his foot, knee, hip, ribs, and shoulder.
c. When a boxer gets punched, she should move her head away from the punch to increase the contact time and reduce the force.
d. A dropped dish is more likely to survive a fall on carpet rather than concrete, because the softness of the carpet leads to increased contact time.