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प्रश्न
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
A green plant is carrying out photosynthesis.
उत्तर
Photosynthesis is taking place in a green plant; no work is being done here because there is no direct displacement.
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संबंधित प्रश्न
Can there be displacement of an object in the absence of any force acting on it? Think. Discuss this question with your friends and teacher.
A force acts on a body and displaces it by a distance S in a direction at an angle θ with the direction of the force. What should be the value of θ to get the maximum positive work?
Define work.
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.
Name the forms of energy which a wound-up watch spring possesses.
Explain by an example that a body may possess energy even when it is not in motion.
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?
In which of the following case the work done by a force will be maximum : when the angle between the direction of force and direction of motion is 0° or 90°?
P, Q and R are three forces which act as shown in fig.
The point O lies in the same plane. Given, P = Q = R = 10N
(i) Which force has the least moment about O? Give a reason.
(ii)Which force has the greatest moment about O? Give a reason.
Can work done be zero even if force acts on the body?
How fast should a boy weighting 30 kg run so that his kinetic energy is 375 joule?
State the energy changes which take place when Water stored in the dam is used to turn turbine in dynamo.
State the energy changes which take place when A piece of magnesium wire is burnt in a jar of oxygen.
State the energy changes which take place when A toy car with a wound spring moves on ground.
Give an example
Chemical energy changes to electrical energy.
Explain, why submarines are able to dive underwater as well as a sail on the surface of the water?
