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प्रश्न
What are the quantities on which the amount of work done depends? How are they related to work?
उत्तर
The work done by a force on a body depends on two factors:
(i) Magnitude of force applied
(ii) Displacement in the direction of force applied
The relation between work (W), force (F) and displacement (S) is given by following equation:
W = F.S. cos θ
Where,
(W) - Work done
(F) - Force
(S) - Displacement
(θ) - Angle between the force applied and displacement of the body.
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संबंधित प्रश्न
No work is done by a force if the body
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Fill in the blank with suitable word :
Work is measured as a product of __________ and __________
Define the term 'work'. Write the formula for the work done on a body when a force acts on the body in the direction of its displacement. Give the meaning of each symbol which occurs in the formula.
What is the work done when the object acted upon by a force remains at rest?
On what factors does the work done by a force depend?
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?
A block of mass 30 kg is pulled up a slope, as shown in diagram with a constant speed, by applying a force of 200 N parallel to slope.
A and B are initial and final positions of block.
(i) Calculate the work done by force in moving the block from A to B.
(ii) Calculate P.E. gained by block. [g=10ms-2]
Calculate the work done when:
A 5 kg weight is lifted 10 m vertically. (g = 9.8 m/s2)
A coolie is pushing a box weighing 1500 N up an inclined plane 7.5 m long on to a platform, 2.5 m above the ground.
(i) Calculate the mechanical advantage of the inclined plane. (ii) Calculate the effort applied by the coolie.
(iii) In actual practice, the coolie needs to apply more effort than what is calculated. Give one reason why you think the coolie needs to apply more effort.
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.
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
A donkey is carrying a load on its back.
Work done by this force at any instant is ______.
