Q7 - This problem has two parts. I will type the questions for each of the two parts, and any other additional info in the "Description" below.

Question

Boxing gloves are padded to lessen the force of a blow on both the boxer's hands and the opponent.

Part a) Calculate the magnitude of the force, in newtons, exerted by a boxing glove on an opponent's face, if the glove and face together compress 7.25 cm during a blow in which the 7.25 kg arm and glove are brought to rest from an initial speed of 9.5 m/s.

Part b) Now calculate the force, in newtons, exerted by an identical blow in the old days when no gloves were used and the knuckles and face would compress only 2.00 cm.

Answer 1

I modified my initial answer where I tried to work this as a momentum-impulse problem.

It makes more sense to treat it as a work-energy problem.

So we start off by setting work (force × distance) equal to

the loss of kinetic kinetic energy of the boxer's hand.

a)

Plug in m = 7.25 kg, v = 9.5 m/s, and x_comp = 7.25 cm = 0.0725 m

to get F = (7.25)(9.5)²/(0.0725)2 = 4512.5 N

b)

with x_comp = 2 cm = 0.02 m

F = (7.25)(9.5)²/(0.02) = 16,358 N