Advertisements
Advertisements
प्रश्न
Is it possible that a force is acting on a body but still the work done is zero? Explain giving one example.
उत्तर
Yes, it is possible that a force is acting on a body but the work done is still zero. Following are the cases:
1. The displacement is zero.
2. The force and displacement are perpendicular to each other.
We know,
W = (F) (S) cos θ
Where,
(W) - Work done
(F) - Force
(S) - Displacement
(θ ) - Angle between force and displacement
From the equation itself, when the displacement is zero the work done is zero.
Example: No work is done when one pushes a wall that remains static even after pushing very hard.
When the force is perpendicular to the direction of motion, , and hence the work done is also zero.
Example - Work done by the force of gravity on a horizontally moving body is zero, because the force of gravity is perpendicular to the horizontal.
APPEARS IN
संबंधित प्रश्न
When do we say that work is done?
Work done = Force × ........................................
A water pump raises 50 litres of water through a height of 25 m in 5 s. Calculate the power of the pump required.
(Take g = 10 N kg-1 and density of water = 1000 kg m-3)
State two disadvantages of producing hydroelectricity.
Fill in the blank with suitable word :
The work done on a body moving in a circular path is __________
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?
Name the physical quantity whose SI unit is Nm.
Complete the following sentences:
Kilowatt is the unit of ....... and kWh is the unit of
A boy pulls a box up to 10 m with a force of 5 kgf. Calculate the work done by him.
Fill in the boxe to show the corresponding energy transformation.
Why is less effort needed to lift a load over an inclined plane as compared to lifting the load directly?
In what way does an ‘Ideal machine’ differ from a ‘Practical machine’?
What should be the characteristic of a source of energy?
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)
A force can cause an object to change its ______.
