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1. A 57 kg boy and a 40 kg girl use an elastic rope while engaged in a tug-of-wa

ID: 1309415 • Letter: 1

Question

1. A 57 kg boy and a 40 kg girl use an elastic rope

while engaged in a tug-of-war on a frictionless

icy surface.

If the acceleration of the girl toward the

boy is 2.3 m/s2, determine the magnitude of

the acceleration of the boy toward the girl.

Answer in units of m/s2

2. A(n) 20.7 g bullet is shot into a(n) 5314 g

wooden block standing on a frictionless sur-

face. The block, with the bullet in it, acquires

a velocity of 1.89 m/s.

Calculate the velocity of the bullet before

striking the block.

Answer in units of m/s

3. A car with mass 1168 kg, moving at 31 m/s,

strikes a(n) 2210 kg car at rest. If the two

cars stick together, with what speed do they

move?

Answer in units of m/s

Explanation / Answer

1) 2.3*(40/57) = 1.614 m/s^2

2) Conservation of momentum so mv is constant.

Total final mass = 5314+20.7 = 5334.7g

Total final momentum = 5334.7 x 1.89 gm/s = 10082.583 gm/s

Bullet's initial momentum = 10082 gm/s

Momentum/mass = velocity

10082/20.7 =487 m/s

c) (mass 1) x (initial velocity of mass 1) + (mass 2) x (initial velocity of mass 2) = (mass 1 + mass 2) x (final velocity of the cars)

1168*31+0= 3378*v

v= 0.346 m/s