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प्रश्न
Define work.
उत्तर १
The definition of work states that when force is applied on a body and the body moves then work is said to be done.
उत्तर २
An action in which one exerts a force to move an object is known as work.
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?
A pair of bullocks exerts a force of 140 N on a plough. The field being ploughed is 15 m long. How much work is done in ploughing the length of the field?
Can there be displacement of an object in the absence of any force acting on it? Think. Discuss this question with your friends and teacher.
In each of the following a force, F is acting on an object of mass, m. The direction of displacement is from west to east, as shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative, positive or zero.
Why is a jack screw provided with a long arm?
Derive a relationship between S.I. and C.C.S. unit of work
State two factors on which the work done on a body depends.
How is work related to energy?
Give reasons for the following. No work is done if a man is pushing against a wall.
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 boy weighing 25 kgf climbs up from the first floor at height 3 m above the ground to the third floor at height 9m above the ground. What will be the increase in his gravitational potential energy? (Take g = 10 N kg -1)
A vessel containing 50 kg of water is placed at a height 15 m above the ground. Assuming the gravitational potential energy at ground to be zero, what will be the gravitational potential energy of water in the vessel? (g = 10 m s-2)
How much energy is gained by a box of mass 20 kg when a man, carrying the box waits for 5 minutes for a bus?
Explain degradation of energy by taking two examples of your daily life.
Is work a scalar or a vector quantity?
Define 1 joule of work.
A car is being driven by a force of 2.5 ✕ 1010 N. Travelling at a constant speed of 5 m/s, it takes 2 minutes to reach a certain place. Calculate the work done.
How much work is done when a force of 2 N moves a body through a distance of 10 cm in the direction of force?
A max X goes to the top of a building by a vertical spiral staircase. Another man Y of the same mass goes to the top of the same building by a slanting ladder. Which of the two does more work against gravity and why?
The work done on an object does not depend on ______.
Name the physical quantity whose SI unit is Nm.
Does the earth move around the sun with a uniform velocity?
What is the work done when the object acted upon by a force remains at rest?
Is work done a scalar or a vector physical quantity?
What is the work done against gravity when a body is moved horizontally along a frictionless surface?
When you move upstairs, do you perform some work?
What do you mean by a kilo joule?
Write an expression for work done by a force depends?
Write an expression for the work done against gravity.
A weight lifted a load of 200 kgf to a height of 2.5 m in 5 s. calculate: (i) the work done, and (ii) the power developed by him. Take g= 10 N kg-1.
A woman pulls a bucket of water of total mass 5 kg from a well which is 10 s. calculate the power used by her.
A boy pulls a box up to 10 m with a force of 5 kgf. Calculate the work done by him.
How fast should a boy weighting 30 kg run so that his kinetic energy is 375 joule?
Fill in the boxe to show the corresponding energy transformation.
State the energy changes which take place when An electric bulb glows when it is connected to a source of electric current.
Give an example
Electrical energy changes to heat energy.
What do you understand by the term energy? Is energy a scalar or vector? How is the energy possessed by a body measured?
Name two places in India where electricity is generated from nuclear power plants.
(i) A 200g ball is thrown vertically upward with an initial velocity of 30 ms-1. Draw a velocity-time graph for the motion of ball.
(ii) How long will the ball take to reach the highest point?
(iii) What will be the kinetic energy of ball, when it returns to the starting point, neglecting the air resistance?
(iv) What will be the potential energy of ball at highest point?
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.
A water pump raises 50 kg of water through a height of 25 m in 5s. Calculate the power supplied by the pump (Take: g = 10 N kg−1).
If a ball is dropped on the sloping roof of a house, it acquires ______ and falls on the ground. That is the transformation of ______ energy into ______ energy takes place.
(kinetic, potential, motion)
One labourer carried four pans of road metal through a distance of 100 metres. If he carries two pans of road metal through a 200 metre distance ______ work will be done.
Write the two main conditions are needed for work to be done?
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
Suma is swimming in a pond.
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.
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
Food grains are getting dried in the sun.
A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car
A man squatting on the ground gets straight up and stand. The force of reaction of ground on the man during the process is ______.
