Question

2. Rocky Balboa punches Apollo Creed in the gut with a force of 225 N, creating an impulse of
45 Ns.
Given Info
A) What was the time of the impact?
B) What was the initial velocity of Rocky's punch during that time, if his hand's mass is 0.5 kg and Rocky's hand
IMP
comes to a stop when he strike's Apollo's Gut? [4.6)
Fnet
m

Answer 1

Answer:

The time of the impact , T = 0.2 sec.

Initial velocity of Rocky's punch during that time, u = 90 $\frac{m}{s}$  

Explanation:

Given, rocky punches with a force, F = 225 N.

And impulse created, P = 45 Ns.

Impulse, P = force × time of impact = F × T.

so, Time of impact, T = $\frac{impulse}{force}$ = $\frac{P}{F}$

T = $\frac{45}{225}$ = 0.2 s.

 Impulse is also change in momentum,

 P = m(v - u). where, m = mass of the hand.

                                  v = final velocity.

                                  u = initial velocity.

Given that Rocky's hand comes to stop when he strikes the gut,

so, v = 0.

⇒  m × u = 45 Ns.

⇒ u = $\frac{45}{m}$ = $\frac{45}{0.5}$

 u = 90 $\frac{m}{s}$