Question

A child of mass 40kg jumps off a wall and hits the ground at 4m\s.he bends his knees and stops in 1s.calculate the force required to slow him down.how would this force be different if he didn't bend his knees and stopped in 0.1s?

Answer 1

F

=

m

Δ

v

t

force = mass * change in velocity / time

at

1

s:

mass:

40

kg

change in velocity (taking downwards as a positive direction):

4

m/s to rest

=

4

−

0

=

4

m/s

time:

1

s

m

Δ

v

t

=

160

1

=

160

force applied

=

160

N

at

0.1

s:

m

Δ

v

t

=

160

0.1

=

1600

force applied =

1600

N