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प्रश्न
The S.I. unit of energy is .............
उत्तर
The S.I. unit of energy is joule.
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संबंधित प्रश्न
When do we say that work is done?
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.
Why is a jack screw provided with a long arm?
A coolie does no work against the force of gravity while carrying a luggage on a road.
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 car is running at a speed of 15 km h-1 while another similar car is moving at a speed of 45 km h-1. Find the ratio of their kinetic energies.
State two disadvantages of producing hydroelectricity.
Each of the following statement describes a force acting. Which force is causing work to be done?
Ravi applied a force of 10 N and moved a book 30 cm in the direction of the force. How much was the work done by Ravi?
What is the SI unit of work?
A weight lifted a load of 200 kgf to a height of 2.5 m in 5 s. calculate: (i) the work done, and (ii) the power developed by him. Take g= 10 N kg-1.
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 coolie, with a load of 30 kg on his head, walks on the platform. If he walks a distance of 60 m, what is the work done by him?
Define Translational motion.
Is power a scalar or a vector quantity?
Name two places in India where electricity is generated from nuclear power plants.
Explain, why submarines are able to dive underwater as well as a sail on the surface of the water?
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?
