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प्रश्न
उत्तर
P.E = mgh = 1 x 10 x 1 = 10J
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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.
State two conditions when no work is done by a force.
Find the kinetic energy of a body of mass 1 kg moving with a uniform velocity of 10 m s-1.
What are the units of (a) work, and (b) energy?
The work done by a force acting obliquely is given by the formula : W = F cos θ ✕ s. What will happen to the work done if angle θ between the direction of force and motion of the body is increased gradually? Will it increase, decrease or remain constant.
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?
State the conditions of equilibrium for a rigid body.
Is the motion of moon around the earth in circular path an accelerated motion?
A man lifts a mass of 10 kg from the floor to a shelf 4 meter high. If g = 10 ms-2, what is the work done?
How many joules are there in 1 mega joule?
(a) Define power and name its unit.
(b) A girl weighting 50 kg climbs up 60 steps each of 20 cm height in 5 minutes. Calculate the power developed.
State the energy changes which take place when A toy car with a wound spring moves on ground.
In what way does an ‘Ideal machine’ differ from a ‘Practical machine’?
Name the material commonly used for the manufacturing of solar cells.
(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?
Calculate the work done when:
A 5 kg weight is lifted 10 m vertically. (g = 9.8 m/s2)
An electric motor of power 100 W is used to drive the stirrer in a water bath. If 50% of the energy supplied to the motor is spent in stirring the water. Calculate the work done on the water in one minute.
