Work Energy and Power Class 11 MCQs. We covered all the Work Energy and Power Class 11 MCQs in this post for free so that you can practice well for the exam.
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Work Energy and Power Class 11 MCQs for Students
A car is moving at a high speed. Which energy does it possess?
(a) Kinetic energy
(b) Potential energy
(c) Frictional force
(d) Gravitational force
Option a – Kinetic energy
An object of mass 20 kg is moving with a uniform velocity of 5 ms 1. What is the kinetic energy possessed by it?
(a) 350 J
(b) 150 J
(c) 200 J
(d) 250 J
Option d – 250 J
Consider the following statements. I. There is no net moment on a body that is in equilibrium. II. The momentum of a body is always conserved. III. The kinetic energy of an object is always conserved. Which of the statements (s) given above is/are correct?
(a) Only I
(b) II and III
(c) I and II
(d) All of the above
Option c – I and II
A raised hammer possesses
(a) kinetic energy
(b) mechanical energy
(c) muscular energy
(d) potential energy
Option d – potential energy
What does the Kinetic Energy (KE) of a moving body depend upon?
(a) Weight and its position
(b) Mass and its position
(c) Mass and velocity
(d) Mass and acceleration
Option c – Mass and velocity
How is the kinetic energy of a moving object affected if the net work done on it is positive?
(a) Decreases
(b) Increases
(c) Remains constant
(d) Becomes zero
Option b – Increases
Assertion (A) Work done by friction on a body sliding down an inclined plane is positive. Reason (R) Work done is greater than zero if the angle between force and displacement is acute. Codes
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Option d – A is false, but R is true
An example of the conservative force is
(a) friction force
(b) gravitational force
(c) viscous force
(d) None of these
Option b – gravitational force
Which one of the following forces is non-central and non-conservative?
(a) Frictional force
(b) Electric force
(c) Gravitational force
(d) Mechanical force
Option a – Frictional force
The energy of a body is
(a) its capacity of doing work.
(b) a scalar quantity.
(c) rate of doing work.
(d) Both (a) and (b)
Option d – Both (a) and (b)
Example of non-conventional sources of energy is
(a) Geothermal energy
(b) Nuclear energy
(c) Wind energy
(d) Both (a) and (b)
Option d – Both (a) and (b)
Which one of the following is not a form of stored energy?
(a) Nuclear energy
(b) Potential energy
(c) Electrical energy
(d) Chemical energy
Option a – Nuclear energy
Mechanical energy is the sum of
(a) kinetic energy + potential energy
(b) chemical energy + electrical energy
(c) potential energy + heat energy
(d) kinetic energy + heat energy
Option a – kinetic energy + potential energy
The SI unit of mechanical energy is
(a) joule
(b) watt
(c) newton-second
(d) joule-second
Option a – joule
The work done by a force is equal to the
(a) scalar product of the force and another displacement.
(b) scalar product of the force and the velocity.
(c) scalar product of the mass and the velocity.
(d) scalar product of the mass and acceleration.
Option a – scalar product of the force and another displacement
A man pushes a wall and fails to displace it. He does
(a) negative work
(b) positive but not maximum work
(c) no work at all
(d) maximum work
Option c – no work at all
If a body is whirled in a circle the work done on it ………
(a) is negative
(b) is zero
(c) cannot be determined
(d) is positive
Option b – is zero
When a body is made to slide over a rough horizontal surface, the work done by the frictional force is
(a) positive
(b) negative
(c) zero
(d) may be positive and negative
Option b – negative
When a body falls freely under gravity then the work done by gravity is
(a) Positive
(b) Negative
(c) Zero
(d) Infinity
Option a – Positive
Calculate the ratio of the rate of work done by a boy of 40 kg and a man of 50 kg if they run up a staircase in 20 seconds and 40 sec respectively.
(A) 8 : 5
(B) 4 : 3
(C) 9:11
(D) 6:12
Option a – 8 : 5
The potential energy (in joule) of a body of mass 2 kg moving in the x-y plane is given by U = 6x + 8y, where the position coordinates x and y are measured in meters. If the body is at rest at point (4 m, 3 m) at time t = 0, then it will cross the y-axis at time t equal to
(A) 1.63 s
(B) 1.2 s
(C) 1.13 s
(D) 2.4 s
Option a – 1.63 s
What will be the kinetic energy of a body of mass kg, 2 m above the ground, when it falls from 10 to a height of 20 m? (g = 10 m/s²)
(A) 1200 J
(B) 2000 J
(C) 1400 J
(D) 1800 J
Option d – 1800 J
Find the K.E. of a block of mass 20 kg moving in x direction with a constant speed of 5 m/s at 30 m, if it is subjected to a resistive force F = 0.2 x J/m during its travel from x = 10 m to 30 m.
(A) 120 J
(B) 150 J
(C) 170 J
(D) 280 J
Option c – 170 J
Two forces 5 N and 8 N act simultaneously on a stationary body of mass 15 kg at right angles to each other and sets it into motion. The kinetic energy of the body at the end of 15 s is
(A) 423.2 J
(B) 555.4 J
(C) 667.5 J
(D) 721.4 J
Option c – 667.5 J
Find the work done in one rotation by a 0.5 hp motor if it runs at a speed of 500 r.p.m with an efficiency of 60%.
(A) 12.64 J
(B) 26.87 J
(C) 13.26 J
(D) 46.48 J
Option b – 26.87 J
What will be the instantaneous power delivered to the body of mass 20 kg for a fraction of time t which accelerates uniformly from rest to 20 m/s in 10 s?
(A) 100 t
(B) 80 t
(C) 20 t
(D) 40 t
Option b – 80 t
Find the maximum acceleration given to a 1000 kg car, moving with a speed of 40 m/s. The engine of the car delivers 50 kW while resistive force due to the surface is 600 N.
(A) 0.65 m/s²
(B) 0.5 m/s²
(C) 1.2 m/s²
(D) 2.6 m/s²
Option a – 0.65 m/s²
What will be the maximum compression of the spring if an object of mass 2 kg strikes it with a speed of 2 m/s? (k = 50 N/m)
(A) 0.1 m
(B) 0.8 m
(C) 0.4 m
(D) 0.2 m
Option c – 0.4 m
Calculate the ratio of the output power of the first man to the second man, if the first man does a given amount of work in 20 seconds and another man does the same amount of work in 25 seconds.
(A) 2 : 3
(B) 5 : 4
(C) 3 : 2
(D) 4 : 5
Option b – 5 : 4
A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle. The motion of the particle takes place in a plane. It follows that
(A) its velocity is constant.
(B) its acceleration is constant.
(C) its kinetic energy is constant.
(D) it moves in a straight line.
Option c – its kinetic energy is constant.
Find the power delivered to the turbine if water is falling on it at a rate of 200 kg/s from a height of 50 m. (g = 10 m/s²)
(A) 400 kW
(B) 100 kW
(C) 50 kW
(D) 200 kW
Option b – 100 kW
A towing van of 100 kW power is required to drag a bus on a horizontal road with a constant speed of 10 m/s. The force exerted by the van will be
(A) 15 kN
(B) 30 kN
(C) 10 kN
(D) 20 kN
Option c – 10 kN
What will be the average power of the engine of a car of mass 600 kg which uniformly accelerates from rest to a velocity of 108 km/hr in 10 s?
(A) 20 kW
(B) 47 kW
(C) 27 kW
(D) 32 kW
Option c – 27 kW
The kinetic energy of a body is directly proportional to
(A) the amount of work required to stop a moving body.
(B) the velocity of a moving body.
(C) the potential energy of a moving body.
(D) acceleration of a moving body.
Option a – the amount of work required to stop a moving body
If a shell fired from a cannon explodes in mid-air, then
(A) its total momentum increases.
(B) its total momentum decreases.
(C) its total energy decreases.
(D) its total kinetic energy increases.
Option d – its total kinetic energy increases
Calculate the increase in kinetic energy of a body of mass 10 kg having the momentum of 10 kg m/s when a force of 3 N is applied to it for 10 s.
(A) 30 J
(B) 80 J
(C) 20 J
(D) 75 J
Option d – 75 J
Find the ratio of velocities of a nucleus that splits into two nuclear parts having radii in the ratio 1 : 4.
(A) 4 : 1
(B) 8 : 1
(C) 64 : 1
(D) 32 : 1
Option c – 64 : 1
Calculate power to be supplied to a motor boat to move with a speed of 4 m/s when hit by water with a force of 300 N. ( Work and Energy Class 11 MCQs )
(A) 0.5 kW
(B) 1.2 kW
(C) 1.8 kW
(D) 1.5 kW
Option b – 1.2 kW
A bomb of mass 6 kg divides into two parts whose ratio of masses is 1 4. Calculate the momentum of the bigger part if the kinetic energy of the smaller part is 200 J.
(A) 22 kg m/s
(B) 33 kg m/s
(C) 44 kg m/s
(D) 11 kg m/s
Option a – 22 kg m/s
Find the ratio of the masses of two bodies having kinetic energies in the ratio 5 : 1 and moving with equal liner momentum.
(A) 5 : 1
(B) 10 : 1
(C) 1:10
(D) 1 : 5
Option d – 1 : 5
Calculate the amount of work required to raise the ladder from the horizontal position to the vertical position, when it is 3 m long with a weight of 200 N, has its center of gravity 1 m from its bottom, and a weight of 50 N attached to its top end.
(A) 450 J
(B) 150 J
(C) 250 J
(D) 350 J
Option d – 350 J
A spring stores an energy of 50 J when it is stretched by 2 cm. If it is further stretched by 2 cm, the stored energy will be increased by
(A) 150 J
(B) 90 J
(C) 180 J
(D) 300 J
Option a – 150 J
A block of 2 kg at rest starts moving under the action of 20 N force. If the coefficient of friction between the block and the floor is 0.3 then, work done by the force in 5 s is (Take g = 10 m/s²)
(A) 900 J
(B) 1750 J
(C) 1240 J
(D) 2341 J
Option b – 1750 J
Two solid balls of mass 4 kg and 3 kg respectively move in the opposite direction with a velocity of 0.4 m/s and x m/s. After the collision, the two balls come to rest then the value of x will be,
(A) – 0.28 m/s
(B) -0.64 m/s
(C) -0.15 m/s
(D) -0.53 m/s
Option d – -0.53 m/s
Find the work done by a man against gravity, if he carries a stone of 10 kg on his head on a level road. ( Work and Energy Class 11 MCQs )
(A) Zero
(B) 40 J
(C) 10 J
(D) 20 J
Option a – Zero
Calculate work done in displacing a particle from x = 0 to x = 5 m under the application of a force F = (0.2x + 10) N.
(A) 23.45 J
(B) 62.3 J
(C) 46.4 J
(D) 52.5 J
Option d – 52.5 J
Calculate the work done by a force of 6 N in maintaining a velocity of 4 m/s of 8 kg block for one minute.
(A) 1440 J
(B) 1860 J
(C) 1960 J
(D) 1206 J
Option a – 1440 J
Find the combined velocity of two objects after collision if mass of two objects are 1 kg and 2 kg respectively and their velocity before collision are 4 m/s and 0 m/s respectively
(A) 4.96 m/s
(B) 2.33 m/s
(C) 6.48 m/s
(D) 1.33 m/s
Option d – 1.33 m/s
A packet is resting on a smooth horizontal plane making an angle of 30° with the horizontal. When work of 20 J is done on the packet, it gets displaced by 5 m. The force applied on the packet is
(A) 4.61 N
(B) 5.28 N
(C) 3.64 N
(D) 6.23 N
Option a – 4.61 N
The ratio of the relative velocity of separation after a collision to the relative velocity of approach before the collision between two colliding bodies is ……..
(A) the velocity of collision
(B) the sum of the velocities
(C) the resultant velocity
(D) the coefficient of restitution
Option d – the coefficient of restitution
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