General
✓✗A 100 W bulb is lit for 10 hours. The energy consumed is
- 10 kWh
- 1 kWh
- 0.1 kWh
- 100 kWh
General
✓✗Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional forces are 10% of the input energy. How much power is generated by the turbine? (g = 10 m s−2)
- 8.1 kW
- 12.3 kW
- 10.2 kW
- 7.0 kW
General
✓✗A particle moves in a vertical circle on a light rigid rod (not a string). The minimum speed at the lowest point needed to complete the circle is
- \( \sqrt{5gl} \)
- \( \sqrt{3gl} \)
- \( \sqrt{gl} \)
- \( \sqrt{4gl} \)
General
✓✗A pendulum bob passes through its lowest point at 2 m s−1. The maximum height it rises above the lowest point is (g = 10 m s−2)
- 0.4 m
- 2 m
- 0.2 m
- 0.1 m
General
✓✗A stone tied to a string of length 0.9 m is whirled in a vertical circle. The minimum speed at the highest point for the string to remain taut is (g = 10 m s−2)
- 3 m s−1
- \( \sqrt{3} \) m s−1
- 0.9 m s−1
- 9 m s−1
General
✓✗A body slides down a smooth incline. Its
- kinetic energy decreases
- total mechanical energy decreases
- potential energy decreases and kinetic energy increases
- potential energy increases
General
✓✗A body is thrown up from the ground with 20 m s−1. At what height is its kinetic energy equal to its potential energy? (g = 10 m s−2)
- 10 m
- 20 m
- 15 m
- 5 m
General
✓✗A ball dropped from height h bounces on a floor with coefficient of restitution e. The total time taken before it stops bouncing is
- \( \sqrt{\dfrac{2h}{g}}\,(1 + e) \)
- \( \sqrt{\dfrac{2h}{g}}\,\dfrac{1 + e}{1 - e} \)
- \( \sqrt{\dfrac{2h}{g}}\,\dfrac{1 - e}{1 + e} \)
- \( \sqrt{\dfrac{2h}{g}}\,\dfrac{1}{1 - e} \)
General
✓✗A spring-loaded toy gun launches a 50 g ball horizontally from a height of 1.25 m. The spring (k = 320 N/m) is compressed by 5 cm. The horizontal range of the ball is (g = 10 m s−2)
- 2 m
- 0.5 m
- 1 m
- 4 m
General
✓✗A spring stores 10 J of energy when compressed by 5 cm. The energy it stores when compressed by 10 cm is
- 20 J
- 10 J
- 40 J
- 80 J
General
✓✗At any instant of time t, the displacement of a particle is given by 2t − 1 (SI unit) under the influence of a force of 5 N. The value of instantaneous power is (in SI unit)
- 7
- 6
- 10
- 5
General
✓✗The potential energy U(x) of a particle is constant over a region. In that region, the force on the particle is
- zero
- infinite
- constant and non-zero
- increasing with x
General
✓✗A force of 10 N moves a body 5 m in the direction of the force. The work done is
- 0.5 J
- 50 J
- 2 J
- 15 J
General
✓✗The gravitational potential energy of a body of mass m at a small height h above the ground (taking the ground as zero) is
- mgh
- mh/g
- \( \dfrac12mgh \)
- mg/h
General
✓✗A vertical spring (k = 500 N/m) is compressed by 20 cm and a 0.25 kg ball is placed on it. When released, the ball rises to a height of (measured from the compressed position; g = 10 m s−2)
- 4 m
- 1 m
- 8 m
- 2 m