Physics – Class 11 Mock Test 5

1. A boy of mass 50kg is standing on a frictionless surface. He throws a ball of mass 2kg away from him with a speed of 10m/s. Find the final speed of the centre of mass.

2. A ball of mass 100 g is moving with a velocity of 3 m/s towards east. A cube of mass 200 gram is moving towards west with a velocity of 7 m/s. If the collision is perfectly elastic, what is the final velocity of the cube in m/s?

3. A ball of mass 3 kg and a ball of mass 2 kg roll towards each other on a flat surface. How far is the centre of mass from the 3 kg ball of the 2 balls are separated by 6 m?

4. Four objects of mass 1 kg each are placed on 4 corners of a square of side 1 m as shown in the figure. Consider “O” to be the origin. What is the position of the centre of mass?

5. A ball of mass 2kg is moving with a speed of 10m/s along a flat surface. It collides with another ball of mass 3kg and comes to rest, what will be the speed of the second ball after collision?

6. From the figure, find out the perpendicular distance of the centre of mass of the system from side AB. ABCD is a square of side 2 m.

7. A 200 kg wagon climbs up a hill of slope 30-degrees in 1 minute at a speed of 10 m/s. How much power is delivered by the engine? (Assume g = 10m/s²)

8. A particle of mass 5kg is rotating about an axis in a circle with a speed of 10m/s. What should be its radius so that the component of angular momentum about the axis is 5kgm²/s?

9. When two same masses travelling in opposite directions with different velocities collide perfectly elastically, their velocities ______

10. A ring is rotating about a diameter. The radius = 5cm & mass of ring = 1kg. A force is applied on the ring such that it is perpendicular to the axis and vector AB as shown in the figure. The magnitude of force is 10N. Find the work done by the torque, when the ring rotates by 90°.