Q.11)-The function of ball bearings in a wheel is
- To increase friction
- To convert kinetic friction into rolling friction
- To convert static friction into kinetic friction
- Just for convenience
Q.12)-A sphere rolls down on two inclined planes of different angles but same heights, it does so
- In the same time
- With the same speed
- In the same time with the same speed
- In the same time with the same kinetic energy
Q.13)-An athlete runs before long jump to get advantage on
- Inertia of motion
- Frictional force
- Moment of a force
- Principle of moments
Q.14)-A pilot has to release the bomb to hit a target
- Right above the target
- Beyond the target
- Before the target
- None of these
Q.15)-A bomb at rest explodes into a large number of tiny fragments.The total momentum of all the fragments.
- Is zero
- Depends on the total mass of all the fragments
- Depends on the speeds of various fragments
- Is infinity
Q.16)-The slope of a velocity time graph represents
- Acceleration
- Displacement
- Distance
- Speed
Q.17)-Railway tracks are banked on curves so that
- Necessary centrifugal force may be obtained from the horizontal component of the weight of the train
- No frictional force may be produced between the tracks and the wheels of the train
- Necessary centripetal force may be obtained from the horizontal component of the weight of the train
- The train may not fall down inwards
Q.18)- When a running car stops suddenly the passengers tends to lean forward because of
- Centrifugal force
- Inetria of rest
- Inertia of motion
- Gravitational force
Q.19)-A metal ball and a rubber ball, both having the same mass, strike a wall normally with the same velocity.the rubber ball rebounds and the metal ball does not rebound. It can be concluded that
- The rubber ball suffers greater change in momentum
- The metal ball suffers greater change in momentum
- Both suffer the same change in momentum
- The initial momentum of the rubber ball is greater than that of the metal ball
Q.20)-The motion of the wheels of a bullock cart while moving on the road is an example of
- Oscillatory and rotatory motion
- Oscillatory and translatory motion
- Translatory and rotatory motion
- Translatory motion only