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State the S.I. unit of work and define it.
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.
In which of the following cases, is work being done?
(i) A man pushing a wall.
(ii) a coolie standing with a load of 12 kgf on his head.
(iii) A boy climbing up a staircase.
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
How much work is done when a body of mass m is raised to a height h above the ground?
Determine the amount of work done when an object is displaced at an angle of 30° with respect to the direction of the applied force.
Name the force acting away from the centre of circular path.
What is the work done when the object acted upon by a force remains at rest?
Complete the following sentences:
The SI unit of work is ....... and of power is .......
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.
Give an example
Electrical energy changes to heat energy.
Can two agents, doing the same work, have different power?
Explain, why submarines are able to dive underwater as well as a sail on the surface of the water?
(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 bucketful of water is to be drawn from a well ______ will be done when a ______ is applied to do this because there will be a ______ of water.
(displacement, work, force)
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.
