WORKSHEET # 2
1.Calculate the momentum of an object if:
(a)its mass is 4.0 kg and its velocity is 8.0 ms-1
(b)its mass is 500 kg and its velocity is 3.0 kms-1
(c)a force of 20 N is applied to it for 6.0 s and it moves from rest (d)its mass is 2.0 kg and it falls from rest for 10 s (assuming g = 10 ms-1 or 10 Nkg-1).
2.A car of 1200 kg is pushed along a level road by two men. If they use a force of 800 N and frictional forces acting against them are 560 N, calculate: (a)the work done by the men they push the car for 10 m (b)the momentum gained by the car if the men push for 10 s.
3.A railway truck traveling along level track at 9 ms-1 collides with, and becomes coupled to, a stationary truck. Find the velocity of the coupled trucks immediately after the collision if the stationary truck has a mass which is: (a)equal to the mass of the moving truck
(b)twice the mass of the moving truck.
4.Two planes of the same mass collide head-on and become tangled so that they move on together. If the engines of both were stopped at the moment of impact and the speeds of the planes at impact were 120 ms-1 and 200 ms-1, find the joint velocity immediately after collision.
5.Two boys of masses 45 kg and 60 kg sit facing one another on light frictionless trolleys holding the ends of a strong taut cord between them. The lighter boy tugs the cord and acquires a velocity of 2 ms-1. What is the initial velocity of the other boy?
6.To make a course correction, a spaceship fires 5 kg of fuel out of its rocket engines as hot gases moving at 10000 ms-1. If the mass of the spacecraft is 20000 kg, calculate its change of velocity. Assume that the mass of the spaceship remains constant.