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संबंधित प्रश्न
A force of 7 N acts on an object. The displacement is, say 8 m, in the direction of the force (see the given figure). Let us take it that the force acts on the object through the displacement. What is the work done in this case?
In which of the following cases is work being done:
- A boy pushing a heavy rock
- A boy climbing up the stairs
- A coolie standing with a box on his head
- A girl moving on the road.
State the S.I. unit of energy.
Give reasons for the following A teacher moving around in the class is doing work but a child standing and reading a book is not doing any work.
A boy of mass 40 kg climbs up the stairs and reaches the roof at a height 8 m in 5 s. Calculate:
- the force of gravity acting on the boy,
- the work done by him against the force of gravity,
- the power spent by boy. (Take g = 10 m s-2)
What is the condition for a force to do work on a body?
A person of mass 50 kg climbs a tower of height 72 metres. Calculate the work done. (g = 9.8 m s−2).
What happens to the work done when the dispacement of body is at right angles to the direction of force acting on it? Explain your answer.
How much work is done by the gravitational force of earth acting on a satellite moving around it in a circular path? Give reason for your answer.
What is meant by a translational motion? Give one example.
Draw a neat labeled diagram to show the direction of two forces acting on a body to produce rotation in it. Also mark the point about which rotation takes place.
Complete the following sentences:
Joule is the unit of .......
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.
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?
Define force. Is force a scalar or a vector quantity?
In what way does an ‘Ideal machine’ differ from a ‘Practical machine’?
A force is applied on a body of mass 20 kg moving with a velocity of 40 ms−1. The body attains a velocity of 50 ms−1 in 2 seconds. Calculate the work done by the body.
The weights of two bodies are 2.0 N and 2.0 kgf respectively what is the mass of each body?
