71). Recoil of a gun is an example of :
| A). conservation of mass |
| B). conservation of energy |
| C). conversion of P.E. into K.E. |
| D). conservation of linear momentum |
|
72). The universal law of gravitation was propounded by
| A). Kelper |
| B). Galileo |
| C). Newton |
| D). Copernicus |
|
73). The gravitational force with which the sun attracts the earth
| A). is less than the force with which the earth attracts the sun |
| B). is the same as the force with which earth attracts the sun |
| C). is more than the force with which the earth attracts the sun |
| D). is constant throughout the year |
|
74). lf the distance between the earth and the sun were twice what it is now, the gravitational force exerted on the earth by the sun would be
| A). twice as large as it is now |
| B). four times as large as it is now |
| C). half of what it is now |
| D). one-fourth of what it is now |
|
75). The mass of a body is different from its weight because
| A). mass is a variable quantity whereas weight is constant |
| B). mass varies very little at different places whereas weight varies a lot |
| C). mass is constant but weight increases as the body moves from the poles to the equator |
| D). mass is a measure of the quantity of matter whereas weight is a force |
|
76). The weight of a body is .
| A). the same everywhere on the surface of the earth |
| B). maximum at the poles |
| C). maximum at the equator |
| D). more on the hills than in the plains |
|
77). A body weighs slightly more at the poles than at the equator because
| A). the earth is flat at the poles |
| B). the earth has the maximum speed of rotation al the equator |
| C). the attractive force at the poles increases due to the ice cap |
| D). none of these |
|
78). Let \( W_{P} \) and \( W_{E} \) be the weights of a body at the north pole and at the equator respectively. If the earth were not rotating then
| A). \( W_{P} \) would be more |
| B). \( W_{P} \) would remain unchanged |
| C). \( W_{E} \) would remain unchanged |
| D). \( W_{E} \) would be less |
|
79). Person weighs more in a lift, which is
| A). moving up with a constant velocity |
| B). moving down with a constant velocity |
| C). accelerating upward |
| D). accelerating downward |
|
80). lf a body is taken from the earth to the moon
| A). its mass will be different but weight will remain the same |
| B). both mass and weight will be different |
| C). its mass will remain the same but weight will be different |
| D). its mass and weight will remain unchanged |
|
