Advertisements
Advertisements
प्रश्न
A coolie is moving on a road with a luggage on his head. Does he perform work against the force of gravity? Give reason for your answer.
Advertisements
उत्तर
No there is no work done against the force of gravity because the displacement and the direction of force are at an angle of 90°.
Explanation:
Walking involves doing the same amount of work against gravity as standing because the weight of the body is the same.
So, the coolie does work against gravity equal to the total weight he is carrying (his body weight and the weight of whatever he is wearing, carrying, etc).
APPEARS IN
संबंधित प्रश्न
When do we say that work is done?
An electron emitter must have _____________ work function and ___________ melting point.
Define 1 joule of energy.
What is the condition for a force to do work on a body?
A boy does work when he pushes against a brick wall. (yes/no).
List any six forms of energy and write a short note on each of them.
A coolie is pushing a box weighing 1500 N up an inclined plane 7.5 m long on to a platform, 2.5 m above the ground.
(i) Calculate the mechanical advantage of the inclined plane. (ii) Calculate the effort applied by the coolie.
(iii) In actual practice, the coolie needs to apply more effort than what is calculated. Give one reason why you think the coolie needs to apply more effort.
An electric motor of power 100 W is used to drive the stirrer in a water bath. If 50% of the energy supplied to the motor is spent in stirring the water. Calculate the work done on the water in one minute.
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.
