When you jump from an elevated position you usually bend your knees upon reaching the ground. by doing this, you make the time of the impact about 10 times as great as for a stiff-legged landing. in this way the average force your body experiences is a) less than 1/10 as great. b) more than 1/10 as great. c) about 1/10 as great. d) about 10 times as great.
10 time smaller
Since the average force of impact is the impulse divided by the time of impact:
whereas impulse is the change of momentum (from full to rest) which is constant and independent of the time of impact. So if you make the time of the impact about 10 times as great as for a stiff-legged landing, the average force that you experience would be 10 times smaller.
C) about 1/10 as great.
We use the relation between Impulse, I, and momentum, p:
the final speed is zero
We can see that the average Force is inversely proportional to the time, so if the time is 10 times bigger, the average Force is 1/10 as great
c. about 1/10 as great.
While jumping form a certain height when we bend our knees upon reaching the ground such that the time taken to come to complete rest is increased by 10 times then the impact force gets reduced to one-tenth of the initial value when we would not do so.
This is in accordance with the Newton's second law of motion which states that the rate of change in velocity is directly proportional to the force applied on the body.
since mass is constant
the body will experience the tenth part of the maximum force.
represents the rate of change in dependent quantity with respect to time
mass of the person jumping
velocity of the body while hitting the ground.