Advertisements
Advertisements
प्रश्न
State the condition when the work done by a force is positive. Explain with the help of examples.
Advertisements
उत्तर
If the displacement of the body is in the direction of force, then work done is positive.
Hence, W= F × S
For example: A coolie does work on the load when he raises it up against the force of gravity. The force exerted by coolie (=mg) and displacement, both are in upward direction.
APPEARS IN
संबंधित प्रश्न
When a body is placed on a table top, it exerts a force equal to its weight downwards on the table top but does not move or fall
1) Name the force exerted by the table top
2) What is the direction of the force?
What do you mean by equilibrium of a body?
How much force is applied on a body when 150 J of work is done in displacing the body through a distance of 10 m in the direction of the force?
A boy takes 3 minutes to lift a 20 litre water bucket from a 20 m deep well, while his father does it in 2 minutes.
How much work each does? Take density of water = 103 kg m-3 and g = 9.8 N kg-1.
Give the units of couple.
In the following case write yes, if the work is being done and no if no work is being done.
A man moving on the rough ground.
State the practical unit mainly used in mechanical engineering and write down its equivalent in watt.
A man weighing 700 N runs up a flight of 15 steps, each 20 cm high, in 5 seconds. Calculate the power of the man.
A man raises a box of mass 50 kg to a height of 2 m in 20 s, while another man raises the same box to the same height in 50 s. Compare:
- the work done, and
- the power developed by them. Take g = 10 N kg-1
