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प्रश्न
State whether work is done or not, by writing yes or no, in the following case:
A boy climbs up 20 stairs.
पर्याय
Yes
No
उत्तर
Yes
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.
An electron emitter must have _____________ work function and ___________ melting point.
A coolie does no work against the force of gravity while carrying a luggage on a road.
State the SI unit of work.
Explain by an example that a body may possess energy even when it is not in motion.
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.
In case of negative work, the angle between the force and displacement is :
How fast should a boy weighting 30 kg run so that his kinetic energy is 375 joule?
A body of mass 60 kg has the momentum 3000 kgm/s-1. Calculate: the speed of the body.
In the following case write yes, if the work is being done and no if no work is being done.
A coolie standing with a heavy load on his head
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?
A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car
