You kick a soccer ball of mass 0.41 kg. The ball leaves your foot with an initia

Question

You kick a soccer ball of mass 0.41 kg. The ball leaves your foot with an initial speed of 20 m/s.

(a) What is the magnitude of the impulse imparted to the ball by you?
N·s

(b) If your foot is in contact with the ball for 7.0 ms, what is the magnitude of the average force exerted by your foot on the ball?
kN

A 51-g handball moving with a speed of 4.6 m/s strikes the wall at an angle of 32° with the normal, and then bounces off with the same speed at the same angle with the normal. It is in contact with the wall for 2.0 ms. What is the average force exerted by the ball on the wall?
___N

Explanation / Answer

m =0.41 kg, u =20 m/s

(a) impulse = change in momentum = 0.41*20 = 8.2 N.s

(b) F = impulse/time = 8.2/0.007 = 1.17 kN

m = 51 g, u =4.6 m/s,t = 2 ms

u = 4.6 sin(32)i + 4.6 cos(32)j

v = -4.6sin(32)i +4.6 cos(32)j

F = impulse/time = 2musin(32)/t

F =2*51*4.6*sin(32)/0.002=124319 N

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