81). A ball tied with a string to a rotating shaft revolve at uniform speed. As the shaft is suddenly brought to rest the string starts getting round the shaft with the angular velocity of the ball
| A). increasing |
| B). decreasing |
| C). remaining constant |
| D). becoming zero |
|
82). One finds it more difficult to walk on ice than on a concrete road because
| A). ice is soft and spongy whereas concrete is hard |
| B). the friction between the ice and the feet is less than that between the concrete and the feet |
| C). there is more friction on ice than on concrete |
| D). none of these |
|
83). It is easier to roll a barrel than to pull it because
| A). the full weight of the barrel comes into play when it is pulled |
| B). rolling friction is much less than sliding friction |
| C). the surface area of the barrel in contact with the road is more in the case of pulling |
| D). of a reason other than those mentioned |
|
84). A sheet of paper can be pulled out quickly from under a glass of water without spilling the water. This phenomenon illustrates
| A). lack of friction between paper and glass |
| B). Newton's third law of motion |
| C). inertia |
| D). acceleration |
|
85). A horse pulling a tonga moves forward due to the force exerted by
| A). the tonga on the horse |
| B). the horse on the tonga |
| C). the horse on the ground with his feet |
| D). the ground on the horse's feet |
|
86). When the velocity of a body is doubled, its
| A). acceleration is doubled |
| B). momentum is doubled |
| C). kinetic energy is doubled |
| D). potential energy is doubled |
|
87). If two bodies, one heavy and one light, are acted upon by the same force for the same time, then both bodies acquire the
| A). same velocity |
| B). same momentum |
| C). same acceleration |
| D). none of these |
|
88). The work done in holding a weight of 20 kg at a height of 1 m above the ground is
| A). zero |
| B). 20 J |
| C). 200 J |
| D). none of these |
|
89). When the speed of a body is doubled, its kinetic energy becomes
| A). double |
| B). half |
| C). quadruple |
| D). one-fourth |
|
90). Winding a watch is actually the process of storing
| A). electrical energy |
| B). pressure energy |
| C). kinetic energy |
| D). potential energy |
|
