Advertisements
Advertisements
प्रश्न
A block of mass 30 kg is pulled up a slope, as shown in diagram with a constant speed, by applying a force of 200 N parallel to slope.
A and B are initial and final positions of block.
(i) Calculate the work done by force in moving the block from A to B.
(ii) Calculate P.E. gained by block. [g=10ms-2]
उत्तर
(i) Work done in moving the block from = F × d
A to B = 200 N × 3m = 600 J
(ii) Gain in potential energy = mgh = 30 × 10 × 1.5 = 450 J.
APPEARS IN
संबंधित प्रश्न
Define 1 J of work.
In which of the following cases is work being done:
- A boy pushing a heavy rock
- A boy climbing up the stairs
- A coolie standing with a box on his head
- A girl moving on the road.
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.
Differentiate between energy and power.
A boy of mass 40 kg climbs up the stairs and reaches the roof at a height 8 m in 5 s. Calculate:
- the force of gravity acting on the boy,
- the work done by him against the force of gravity,
- the power spent by boy. (Take g = 10 m s-2)
A weight lifter lifted a load of 200 kgf to a height of 2.5 m in 5 s. Calculate:
- the work done, and
- the power developed by him. Take g = 10 N kg-1
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 body of mass 5 kg falls from a height of 10 m to 4 m. Calculate:
The loss in potential energy of the body,
What is the condition for a force to do work on a body?
If the work done by a force in moving an object through a distance of 20 cm is 24.2 J, what is the magnitude of the force?
State the conditions of equilibrium for a rigid body.
Define 'joule'.
A boy pulls a box up to 10 m with a force of 5 kgf. Calculate the work done by him.
Define Translational motion.
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.
A girl of mass 40 kg runs a height of 80 stairs, each 25 cm high with a load of 20 kg on her head in 25 sec. If g is 10 m/s2, find:
(i) Gravitational force acting on the girl.
(ii) Work done by her.
(iii) Useful work done by her.
(iv) Her power in watt.
State whether work is done or not, by writing yes or no, in the following case:
A man pushes a wall.