1. Define the terms work, power, and energy. State
their units and dimensional formulae.
2.
Define potential energy. Give two examples.
Derive an expression for the potential energy.
3.
Define Kinetic energy. Give two examples. Derive
an expression for the Kinetic energy
.
4.
State the law of conservation of energy. Show
that the total energy of a freely falling body is constant throughout its
journey.
5.
State and prove Work-energy theorem. (OR ) Show
that the work done by a force is equal to the change in kinetic energy of the
body.
6.
Define conventional and non conventional energy
sources. Give two examples.
7.
What is the relation between momentum and
kinetic energy of the body?
PROBLEMS
1.
If the momentum of a moving body is doubled, how
does its kinetic energy change?
2.
If the kinetic energy of a given particle is
doubled, how does its momentum change?
3.
An engine of power 1.5 MW applies a force for 56
minutes on a moving train with a velocity of 10 m/s. If there is no friction,
the velocity attained is 25 m/s. Find the mass of the train.
4.
A body of mass 0.02 kg is dropped from a height
30 m. What is the kinetic energy just before it strikes the ground.
5.
A rocket of mass 3 x 104 kg is
launched by applying a constant force of 6 x 105 N for 20 seconds.
Calculate (a) The K.E acquired by the rocket (b) The work done by the force
during this time and (c) power developed in the rocket.
6.
A pump can hoist 7200 kg of coal per hour from a
mine 90 m deep. Find the power if its efficiency is 75%.
7.
If 60 kgms-1 is the momentum of a
body of mass 0.6 kg, find its K.E
.
8.
A stone of mass 10 kg falling from a height 10
m. Find K.E on reaching the ground.
9.
A stone of mass 1 kg is falling freely from a
height 10 m . Find its P.E and K.E after it has travelled a distance of 2 m from
the top.
1.
A machine gun fires 360 bullet per minute and
each bullet travels with a velocity of 600 m/s . If the mass of each bullet is
5 g , find the power of the machine gun.
1.
A man weighing 60 kg lifts a mass of 40 kg to
the top of a building 10 m high in 50 seconds. Find the power exerted by the
man.
1.
A pump can hoist 9000 kg of coal per hour from a
mine of 120 m deep. Find the power its efficiency is 75%.
1.
If the mass of a body reduced to half and the
velocity is doubled, how does its K.E change?
1.
A 5 kg mass is dropped from a height of 10 m .
What is K.E on reaching the ground.
1.
A stone of mass 10 kg falling from a height of
10 m. Find the K.E.
1.
An engine is used to lift water from a well of
depth 60 m to fill a tank of 3m x 4m x 5m in 30 minutes. Find the power of the
engine
.
1.
An engine is used to lift water from a well 50 m
deep to fill a tank of dimensions 5m x 5m x 10m in 50 minutes. Find the power
of the motor if 25% of energy wasted.
1.
Calculate the horse power of the engine required
to lift 1.08 x 106 kg of coal per hour from a mine 74.6 m deep.
