Question

A tractor of mass 5.0×10^3kg is used to tow a car of mass 2.5×10^3kg. The tractor moved with a speed of 3.0m/s,just before the towing rope becomes taut.calculate:
1. The speed of the tractor immediately after the rope becomes taut.
2. loss in kinetic energy of a system just after the car has started moving.
3. impulse in the rope when it jerks a car into motion.

Answer 1

solve

Answer 2

help me solve

Answer 3

initial momentum of system = 3*5*10*3 + 0 = 15*10^3
final momentum of system = v * 5*10^3 + v* 2.5 * 10^3 = v* 7.5*10^3
same momentum before and after (Newton's first thought)
v = 15/7.5 = 2

Ke before = (1/2)(5*10^3) * 9
Ke after = (1/2)(7.5*10^3) * 4
loss = (1/2)(10*3)(45 - 30) Joules

impulse = force on car * time = change in car momentum
= 2.5*10^3 * ( 2 - 0)