Advertisements
Advertisements
प्रश्न
Work done by a boy depends on the time in which he does work.
विकल्प
True
False
उत्तर
False.
APPEARS IN
संबंधित प्रश्न
Write the expression for work done by a force.
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)
The power of a motor is 40 kW. At what speed can the motor raise a load of 20,000 N?
A boy weighing 25 kgf climbs up from the first floor at height 3 m above the ground to the third floor at height 9m above the ground. What will be the increase in his gravitational potential energy? (Take g = 10 N kg -1)
A bullet of mass 0.5 kg slows down from a speed of 5 m s-1 to that of 3 m s-1. Calculate the change in kinetic energy of the ball.
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.
A girl weighing 400 N climbs a vertical ladder. If the value of g be 10 m s−2, the work by her after climbing 2 m will be :
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.
A uniform circular motion is an accelerated motion. Justify it.
Does the earth move around the sun with a uniform velocity?
Write an expression for work done by a force depends?
List any six forms of energy and write a short note on each of them.
State the energy changes which take place when A toy car with a wound spring moves on ground.
State larger units of power.
Explain, why submarines are able to dive underwater as well as a sail on the surface of the water?
(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 body of mass 0.5 kg travels on straight line path with velocity v = (3x2 + 4) m/s. The net work done by the force during its displacement from x = 0 tox = 2 m is ______.