## Physics Quiz 3, Question from Laws of Motion.

1. A wagon weighing 1000 kg is moving with a velocity 50 km/h on smooth horizontal rails. A mass of 250 kg is dropped into it. The velocity with which it moves now is ?

2. The kinetic energy of two masses m1 and m2 are equal. The ratio of their linear momentum will be ?

3. Which of the following has the maximum momentum ?

4. A rocket with a lift-off mass 3.5 x 10 4 kg is blasted upwards with an initial acceleration of 10 m/s 2 Then the initial thrust of the blast is ?

5. In a rocket of mass 1000 kg fuel is consumed at a rate of 40 kg/s. The velocity of the gases ejected from the rocket is 5 x 10 4 m/s . The thrust on the rocket is ?

6. If the force on a rocket moving with a velocity of 300 m/s is 210 N, then the rate of combustion of the fuel is ?

7. A rocket has a mass of 100 kg. 90% of this is fuel. It ejects fuel vapours at the rate of 1 kg/sec with a velocity of 500 m/sec relative to the rocket. It is supposed that the rocket is outside the gravitational field. The initial upthrust on the rocket when it just starts moving upwards is ?

8. A man weighs 80kg. He stands on a weighing scale in a lift which is moving upwards with a uniform acceleration of 5m/s 2. What would be the reading on the scale. (g=10 m/s 2) ?

9.A body of mass 2 kg is hung on a spring balance mounted vertically in a lift. If the lift descends with an acceleration equal to the acceleration due to gravity ‘g’, the reading on the spring balance will be ?