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प्रश्न
Work done by this force at any instant is ______.
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उत्तर
Work done by this force at any instant is zero.
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संबंधित प्रश्न
Define work.
A coolie is moving on a road with a luggage on his head. Does he perform work against the force of gravity? Give reason for your answer.
A vessel containing 50 kg of water is placed at a height 15 m above the ground. Assuming the gravitational potential energy at ground to be zero, what will be the gravitational potential energy of water in the vessel? (g = 10 m s-2)
What should be the angle between the direction of force and the direction of motion of a body so that the work done is zero?
Choose one or more correct alternatives.
For work to be performed, energy must be ______.
- transferred from one place to another
- concentrated
- transformed from one type to another
- destroyed
Give two examples of work done.
Give an example
Electrical energy changes of sound energy.
(i) A 200g ball is thrown vertically upward with an initial velocity of 30 ms-1. Draw a velocity-time graph for the motion of ball.
(ii) How long will the ball take to reach the highest point?
(iii) What will be the kinetic energy of ball, when it returns to the starting point, neglecting the air resistance?
(iv) What will be the potential energy of ball at highest point?
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?
Who is the odd one out?
