Advertisements
Advertisements
प्रश्न
In which of the following cases, is work being done?
(i) A man pushing a wall.
(ii) a coolie standing with a load of 12 kgf on his head.
(iii) A boy climbing up a staircase.
उत्तर
Work is done only in case of a boy climbing up a stair case.
APPEARS IN
संबंधित प्रश्न
Define the term energy.
How is work related to energy?
A machine raises a load of 750 N through a height of 16 m in 5 s. calculate:
- energy spent by machine,
- power at which the machine works.
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)
A boy weighing 25 kgf climbs up from the first floor at height 3 m above the ground to the third floor at height 9m above the ground. What will be the increase in his gravitational potential energy? (Take g = 10 N kg -1)
When is the work done by a force on a body : (a) positive, (b) negative, and (c) zero?
Its moment of a force scalar or a vector quantity?
Draw a neat labeled diagram to show the direction of two forces acting on a body to produce rotation in it. Also mark the point about which rotation takes place.
Explain the difference between a uniform linear motion and a uniform circular motion.
What is the work done against gravity when a body is moved horizontally along a frictionless surface?
No work is done by a man moving on a horizontal road while carrying a box on his head. Explain.
Name the type of energy possessed by a
(i) stretched catapult (ii) hot iron
(iii) wound up clock
Calculate the amount of work done by a child carrying a bag of 20 kg when he moves a distance of 40 m in
(a) Vertical direction, and
(b) Horizontal direction
What do you understand by 'potential energy' and 'Kinetic energy'? Give three examples of each to illustrate your answer.
Is power a scalar or a vector quantity?
A force can cause an object to change its ______.
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
Suma is swimming in a pond.
