Advertisements
Advertisements
प्रश्न
No work is done by a man moving on a horizontal road while carrying a box on his head. Explain.
उत्तर
The displacement of the man and box is along the horizontal direction. Thus, the angle between the displacement and the force of gravity is 900;
Thus, W = Fd cos 900 = 0
Hence, no work is done against gravity in this case; however some work is done against friction.
APPEARS IN
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?
State two conditions when no work is done by a force.
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 is the work done against gravity when a body is moved horizontally along a frictionless surface?
What is meant by a translational motion? Give one example.
Does the earth move around the sun with a uniform velocity?
What is the ratio of SI units to CGS units of 'work'?
Complete the following sentences:
1 H.P. = ........ W.
Fill in the boxe to show the corresponding energy transformation.
A body of mass 60 kg has the momentum 3000 kgm/s-1. Calculate: the speed of the body.
Why is less effort needed to lift a load over an inclined plane as compared to lifting the load directly?
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.
What is power? How do you differentiate kilowatt from kilowatt-hour? The Jog Falls in Karnataka state are nearly 20 m high. 2000 tonnes of waterfalls from it in a minute. Calculate the equivalent power if all this energy can be utilized? (g = 10 m s–2)
Work done by this force at any instant is ______.
