1. A man of mass 70kg stands on a weighing machine in a lift which is moving
(a) upwards with a uniform speed of 10m/s.
(a) downwards with a uniform acceleration of 5m/s2 .
(a) upwards with a uniform acceleration of 5m/s2.
What would be the readings in each case?
(d)what would be the reading if lift mechanism failed and it hurtled down freely under gravity?
2. A shell of mass 0.2kg is fired by a gun of mass 100kg. If the muzzle speed of the shell is 80m/s, what is recoil speed of the gun?
3. A mass of 6kg is suspended by a rope of length 2m from the ceiling. A force of 50N in the horizontal direction is applied at the midpoint P of the rope. What is the angle the rope makes with the vertical in equilibrium.( take g=10m/s2, neglect mass of rope) Q3. Q4.
4. What is the acceleration of the block and trolley system,if the coefficient of kinetic friction between the trolley and the surface is 0.04? What is the tension in the string? (neglect mass of the rope, take g=10m/s2.)
5. Explain the following with appropriate reasons:
(i) What is the source of centripetal force when earth revolves around the sun?
(ii) For uniform circular motion, does the direction of centripetal force depend upon the sense of rotation?
(iii) how do we save petrol when tyres of motorcycle are fully inflated?
(iv) what happens to coefficient of friction when weight of the body is doubled?
(v) why is it easier to maintain the motion than to start it?
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