Q 1 – When a body falls freely towards the earth, then its total energy
(a) increases
(b) decreases
(c) remains constant
(d) first increases and then decreases
Q 2 – A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car
(a) does not change
(b) becomes twice to that of initial
(c) becomes 4 times that of initial
(d) becomes 16 times that of initial
Q 3 – In case of negative work the angle between the force and displacement is (NCERT Exemplar)
(a) 0°
(b) 45°
(c) 90°
(d) 180°
Q 4 – An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass is 3.5 kg. Both spheres are dropped simultaneously from a tower. When they are lo m above the ground, they have the same.
(a) acceleration
(b) momenta
(c) potential energy
(d) kinetic energy
Q 5 – A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be (g = 10 ms²)
(a) 6 × 10³ J
(b) 6 J
(c) 0.6 J
(d) zero
Q 6 – Which one of the following is not the unit of energy?
(a) joule
(b) newton metre
(c) kilowatt
(d) kilowatt hour
Q 7 – The work done on an object does not depend upon the
(a) displacement
(b) force applied
(c) angle between force and displacement
(d) initial velocity of the object
Q 8 – Water stored in a dam possesses
(a) no energy
(b) electrical energy
(c) kinetic energy
(d) potential energy
Q 9 – A body is falling from a height h. After it has fallen a height , it will possess
(a) only potential energy
(b) only kinetic energy
(c) half potential and half kinetic energy
(d) more kinetic and less potential energy
Q 10 – The number of joules contained in 1 kWh is
(a) 36 × 105 J
(b) 3.6 × 107 J
(c) 36 × 108 J
(d) 3.7 × 107 J
Q 11 – Two army persons A and B each of weight of 500 N climb up a rope through a height of 10 m. A takes 20 s while B takes 40 s to achieve this task. What is ratio of the powers of person A and B?
(a) 1 : 2
(b) 1 : 4
(c) 2 : 1
(d) 14 : 1
Q 12 – Which of the following graphs best represents graphical relation between momentum P and kinetic energy K for a body in motion?
Q 13 – If speed of a car becomes 2 times, its kinetic energy becomes
(a) 4 times
(b) 8 times
(c) 16 times
(d) 12 times
Q 14 – Work done by friction
(a) increases kinetic energy of body
(b) decreases kinetic energy of body
(c) increases potential energy of body
(d) decreases potential energy of body.
Q 15 – When a coil spring is compressed, the work is done on the spring. The elastic potential energy
(a) increases
(b) decreases
(c) disappears
(d) remains unchanged
Q 16 – One joule work is said to be done when
(a) a force of 1 N displaces a body by 1 cm
(b) a force of 1 N displaces a body by 1 m
(c) a force of 1 dyne displaces a body by 1 m
(d) a force of 1 dyne displaces a body by 1 cm
Q 17 – SI unit of power is
(a) watt
(b) joule
(c) newton
(d) metre
Q 18 – Mechanical energy of a body includes
(a) kinetic energy only
(b) potential energy only
(c) kinetic energy and potential energy
(d) none of these
Q 19 – Commercial unit of energy is
(a) joule
(b) kWh
(c) watt
(d) newton
Q 20 – Potential energy of a body depends on its
(a) position
(b) configuration
(c) position and configuration
(d) mass and velocity
Q 21 – Work done by centripetal force is
(a) >0
(b) ≥0
(c) <0
(d) 0
Q 22 – When a body f alls freely towards the earth, then its total energy
(a) Decreases
(b) Increases
(c) First increases and then decreases
(d) Remains constant
Q 23 – If work is done at a f aster rate, then
(a) power is more
(b) No power is required to do work
(c) power is less
(d) Infinite power is required
Q 24 – Moon revolves around the earth due to gravitational force (F) of earth on moon. The work done by the gravitational force is (r = radius of circular orbit of moon)
(a) F.2πr
(b) F. πr
(c) zero
(d) negative work
Q 25 – Work done by a body is
(a) negative, positive or zero
(b) always positive
(c) always zero
(d) always negative
Q 26 – 1 W. S = ________?
(a) 10 joule
(b) 1 joule
(c) 3.6 × 106 joule
(d) 2 joule
Q 27 – Scientifically, work is said to be done in which of the following cases
(a) Manish pulls the trolley f or a certain distance
(b) Mira studies f or her exam
(c) Manoj pushes the wall with no change in the position of wall
(d) Mira pulls the wall with no change in the position of wall
Q 28 – P.E of a spring increases when it is in the state of
(a) compression
(b) neither a nor b
(c) expansion
(d) both a and b
Q 29 – When speed of the moving object is doubled its
(a) Acceleration is doubled
(b) Momentum becomes f our times more
(c) K E. is increased to f our times
(d) Potential energy is increased
Q 30 – A ball is thrown vertically upwards. Its velocity keeps on decreasing. What happens to its kinetic
energy when its reaches the maximum height?
(a) Kinetic energy is double
(b) Kinetic energy is zero
(c) Kinetic energy is maximum at maximum height
(d) Kinetic energy is half of initial value
Q 31 – A stone weighing 1 kg is dropped from rest from a height of 4 metres above the ground. When it
has free-fallen1 metre its total energy with respect to the ground is
(a) 15 J
(b) 40 J
(c) 20 J
(d) 30 J
Q 32 – The energy possessed by an oscillating pendulum of a clock is
(a) kinetic energy
(b) potential energy
(c) restoring energy
(d) mechanical energy
Q 33 – What is the commercial unit of energy?
(a) electron volt
(b) W/s
(c) kW h
(d) joule
Q 34 – Calculate the work done in moving a body of mass 50 Kg through a height of 5 m.(g = 10m/s2)
(a) 250 J
(b) 2500 J
(c) 25 x 103 J
(d) 2.5 x 105 J
Q 35 – Find the correct statement
(a) 1 Gigawatt is equal to 109W
(b) power is the rate of doing work
(c) both a and b
(d) none of these
Q 36 – If a f orce of F newton moves a body with constant speed v, the power delivered by it is
(a) F/v
(b) Fv
(c) F2v
(d) v/F
Q 37 – According to the law of conservation of energy
(a) Energy can’t be destroyed
(b) Energy can’t be created
(c) Energy can be transformed from one from to another
(d) All of the above
Q 38 – In SI system, the unit of P.E. is
(a) erg
(b) dyne-cm
(c) J
(d) None of these
Q 39 – In the SI system, the unit of potential energy is
(a) newton
(b) joule
(c) watt
(d) metre per second
Q 40 – Two bodies of equal weight are kept at heights of h and 1.5 A, respectively. The ratio of their PE is
(a) 3 : 2
(b) 2 : 3
(c) 1 : 1
(d) 4 : 3
Q 41 – On tripling the speed of motion of a body, the change in K.E. is
(a) 9 times
(b) 8 times
(c) 4 times
(d) 2 times
Q 42 – A stone is tied to a string and whirled in a circular path. The work done by the stone is :
(a) negative
(b) zero
(c) positive
(d) none of the above
Q 43 – 9800 joule of energy was spent to raise a mass of 50kg, the mass was raised to a height of
(a) 20m
(b) 980m
(c) 10m
(d) none of these
Q 44 – The linear momentum of a body of mass 2kg is 16kgms-1. What is its K. E?
(a) 64J
(b) 70J
(c) 60J
(d) none of these
Q 45 – Potential energy and kinetic energy are types of
(a) Electrical energy
(b) Magnetic energy
(c) Thermal energy
(d) Mechanical energy
Q 46 – A body of mass 5 kg is moving with an acceleration of 5 ms-2 gets a displacement of 2m, the work done by the force is:
(a) 75 J
(b) 25 J
(c) 100 J
(d) 50 J
Q 47 – Work done is said to be positive when a f orce causes displacement:
(a) In its own direction
(b) In the direction opposite to the applied f orce
(c) In the direction at right angles to the direction of applied f orce
(d) None of the above
Q 48 – Two masses m and 2m are dropped f rom certain height ‘h’. Then on reaching the ground,
(a) K.E. of them will be equal
(b) K.E. of the heavier is 4 times the K.E. of the lighter
(c) K.E. of the lighter is 4 times the K.E. of the heavier
(d) K.E. of the heavier is more than that of the lighter
Q 49 – A rocket rises up in the air due to the force generated by the fuel. The work done by the:
(a) fuel is negative work and that of force of gravity is positive work
(b) fuel is positive work and that of force of gravity is negative work
(c) both fuel and force of gravity do positive work
(d) both fuel and force of gravity do negative work
Q 50 – A body is moved through a distance of 3 m in the following different ways. In which case is the maximum work done?
(a) when pushed over an inclined plane
(b) when lifted vertically upward
(c) when pushed over smooth rollers
(d) when pushed on a plain horizontal surf ace
Q 51 – An electric lamp of 100w is used f or 5 hours per day calculate the units of energy consumed by
lamp in one day
(a) 1 unit
(b) 0.5 unit
(c) 1.5 units
(d) none of these
Q 52 – One unit of electricity is consumed by
A : P = 40 W bulb used f or t = 25 hours
B : P = 20 W bulb used f or t = 50 hours
Both A and B are true as, energy E in kWh is best related as
(a) E = Pt
(b) E = Pt/1000
(c) E = P/1000
(d) E = t/1000
Q 53 – Work done by the gravitational f orce of earth on a satellite along a circular path is
(a) O
(b) minimum
(c) max
(d) all of these
Q 54 – In which case work is not done:
(a) A girl swimming in a pond
(b) A windmill lifting water from a well
(c) A standing man holding a suit case in his hand
(d) A sail boat moving in the direction of wind
Q 55 – A boy holds a mass on his stretched hand. Then
(a) Work done against gravity is zero.
(b) Muscular energy is used
(c) Both (a) and (b)
(d) Neither (a) nor (b)