Show, using the equation F = ma, how the impulse of a force F is related to the change in momentum Δp that it produces for a mass m with acceleration a.
A railway truck on a level, straight track is initially at rest. The truck is given a quick, horizontal push by an engine so that it now rolls along the track.
The engine is in contact with the truck for a time T = 0.60 s and the initial speed of the truck after the push is 5.5 m s–1. The mass of the truck is 3.1 × 103 kg.
Due to the push, a force of magnitude F is exerted by the engine on the truck. The sketch shows how F varies with contact time t.
(b)
Determine the magnitude of the maximum force exerted by the engine on the truck.
Two identical blocks A and B of mass 200 g are travelling towards each other along a straight line through their centre. Assume that the surface is frictionless.
Both blocks are moving at a speed of 0.21 m s–1 relative to the surface.
As a result of the collision, the blocks reverse their direction of motion and travel at the same speed as each other. During the collision, 30% of the kinetic energy of the blocks is given off as thermal energy to the surroundings.
(a)
Deduce whether the collision is elastic or inelastic and state your reasoning.
A rocket is travelling at constant velocity in space after exiting the Earth’s atmosphere. The engines are turned off, and a module separates from the rocket.
The module has a mass of 6 000 kg and is ejected at 10 km s–1. The combined mass of the rocket and the module is 81 000 kg and the remaining part of the rocket after the explosion travels at 4500 m s–1 after the module has been ejected.
Inside the rocket, some walls are padded to reduce damage to its interior when it is accelerated into space.
(d)
Explain, with reference to change in momentum, why padded walls are less likely to cause damage to the interior of the rocket compared to a rigid wall.
Joanna and Lindsay are two roller skaters initially at rest on a horizontal surface. They are facing each other and Joanna is holding a ball. Joanna throws the ball to Lindsay who catches it. The speed at which the ball leaves Joanna, measured relative to the ground, is 6.2 m s–1.
The following data are available.
Mass of Joanna = 59 kg
Mass of Lindsay = 64 kg
Mass of ball = 3.3 kg
(a)
(i)
Calculate the velocity v of Joanna relative to the ground immediately after she throws the ball
[3]
(ii) State the direction that Joanna travels in after she throws the ball
Calculate the speed V of Lindsay relative to the ground immediately after she catches the ball. Assume the speed of the ball stays constant throughout its motion.
Lindsay has a previous injury to her hand, so decides to wear padded gloves whilst playing this game with Joanna. This is similar to what players would wear in cricket if they need to catch a ball at high speed.
(d)
Explain why the padded gloves would protect Lindsay’s hands when she catches the ball.
