Advertisements
Advertisements
प्रश्न
Give two examples of work done.
Advertisements
उत्तर
Examples of work done:
(i) In free fall of a body of mass m, under gravity from a height h, the force of gravity (F=mg) is in the direction of displacement (=h) and the work done by the gravity is mgh.
(ii) A coolie lifting a load does work against gravity.
APPEARS IN
संबंधित प्रश्न
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)
Fill in the blank with suitable word :
The work done on a body moving in a circular path is __________
When do we say that work is done? Write the formula for the work done by a body in moving up against gravity. Give the meaning of each symbol which occurs in it.
What should be the angle between the direction of force and the direction of motion of a body so that the work done is zero?
What is the work done against gravity when a body is moved horizontally along a frictionless surface?
State the amount of work done by an object when it moves in a circular path for one complete rotation. Give a reason to justify your answer.
A truck driver can load oil drums into the back of the truck by pushing them up a sloping plank, or by lifting them directly. Each drum has a mass of 80 kg, the plank is 3 m long, and the back of the truck is 0.8 m above the ground.
(i) How much force would be needed to lift a drum into the truck directly/without using the plank? (Take g = 10 m/s2)
(ii) How much energy would be required in lifting the drum into the truck without the plank?
(iii) If the force needed to push the drum up the plank is 300 N, why is this less than the answer to part (i)?
(iv) When the truck is loaded, the driver drives off. List the major energy changes that take place in moving the truck.
(v) The driver has to stop at the factory gates. What happens to the kinetic energy of the truck?
