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प्रश्न
Can work done be zero even if force acts on the body?
उत्तर
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संबंधित 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 sailboat is moving due to wind energy.
Name a common device where a gear train is used
A force of 30 N acts on a body and moves it through a distance of 5 m in the direction of force. Calculate the work done by the force.
Explain degradation of energy by taking two examples of your daily life.
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.
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.
Nm is the unit of .......
A bullet is of mass 'm' g and is moving with a velocity 'v' m/s. Find the kinetic energy of the bullet when
(a) The mass is doubled,
(b) The velocity is tripled.
A body of mass 60 kg has the momentum 3000 kgm/s-1. Calculate: the speed of the body.
Define force. Is force a scalar or a vector quantity?
In the following case write yes, if the work is being done and no if no work is being done.
A boy climbing up a staircase.
What are the advantages and disadvantages of using solar cells for producing electricity?
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?
Calculate the work done when:
A 5 kg weight is lifted 10 m vertically. (g = 9.8 m/s2)
The weights of two bodies are 2.0 N and 2.0 kgf respectively what is the mass of each body?
State whether work is done or not, by writing yes or no, in the following case:
A boy climbs up 20 stairs.
