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An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and the final points of the path of the object lie on the same horizontal line. What is the work done by the force of gravity on the object?
State the S.I. unit of energy.
A weight lifter lifted a load of 200 kgf to a height of 2.5 m in 5 s. Calculate:
- the work done, and
- the power developed by him. Take g = 10 N kg-1
.A man raises a box of mass 50kg to a height of 2m in 20s, while another man raises the same box to the same height in 50s. Compare:
(i) the work done, and
(ii) the power developed by them.
A bullet of mass 0.5 kg slows down from a speed of 5 m s-1 to that of 3 m s-1. Calculate the change in kinetic energy of the ball.
What do you mean by degradation of energy?
Why does a spanner have a long handle?
Is work done a scalar or a vector physical quantity?
What is the ratio of SI units to CGS units of 'work'?
(a) Define power and name its unit.
(b) A girl weighting 50 kg climbs up 60 steps each of 20 cm height in 5 minutes. Calculate the power developed.
A block of mass 20 kg is pulled up a slope (fig.12) with a constant speed by applying a force of 500 N parallel to the slope. A and B are initial and final positions of the block.
(a) Calculate the work done by the force in moving the block from A and B.
(b) Calculate the potential energy gained by the block.
List any six forms of energy and write a short note on each of them.
Fill in the boxe to show the corresponding energy transformation.
Fill in the boxe to show the corresponding energy transformation.
How much energy is gained by a box of mass 20 kg when a man, runs carrying the box with a speed of 3 m/s-1 to catch the bus?
Is power a scalar or a vector quantity?
State the amount of work done by an object when it moves in a circular path for one complete rotation. Give a reason to justify your answer.
Name two places in India where electricity is generated from nuclear power plants.
The weights of two bodies are 2.0 N and 2.0 kgf respectively what is the mass of each body?
A girl of mass 40 kg runs a height of 80 stairs, each 25 cm high with a load of 20 kg on her head in 25 sec. If g is 10 m/s2, find:
(i) Gravitational force acting on the girl.
(ii) Work done by her.
(iii) Useful work done by her.
(iv) Her power in watt.
