JEE-Main (Previous Year Questions)
1. When a rubber-band is stretched by a distance x, it exerts a restoring force of magnitude
F = ax + bx2 where a and b are constants. The work done in stretching the unstretched rubber
band by L is: [JEE(Main)-2014]
aL2 bL3 1 aL2 bL3
(1)
2
+
3
(2)
2 2
+
3
(3) aL2 + bL3 (4)
1
2
(aL2 + bL3 )
2. A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000
times. Assume that the potential energy lost each time he lowers the mass is dissipated. How
much fat will he use up considering the work done only when the weight is lifted up? Fat
supplies 3.8 × 107 J of energy per kg which is converted to mechanical energy with a 20%
efficiency rate. Take g = 9.8 ms–2. [JEE(Main)-2016]
(1) 12.89 × 10 kg
–3
(2) 2.45 × 10 kg
–3
(3) 6.45 × 10–3 kg (4) 9.89 × 10–3 kg
3. A point particle of mass, moves along the uniformly rough track PQR as shown in the figure.
The coefficient of friction, between the particle and the rough track equals . The particle is
released, from rest, from the point P and it comes to rest at a point R. The energies, lost by the
ball, over the parts, PQ and QR, of the track, are equal to each other, and no energy is lost when
particle changes direction from PQ to QR. The values of the coefficient of friction and the
distance x(= QR) are, respectively close to: [JEE(Main)-2016]
(1) 0.29 and 6.5 m (2) 0.2 and 6.5 m
(3) 0.2 and 3.5 m (4) 0.29 and 3.5 m
4. A body of mass m = 10–2 kg is moving in a medium and experiences a frictional force F = –kv2.
1
Its initial speed is v0 = 10 ms–1. If, after 10 s, its energy is mv02 , the value of k will be:
8
[JEE(Main)-2017]
(1) 10–4 kg m–1 (2) 10–1 kg m–1 s–1
(3) 10–3 kg m–1 (4) 10–3 kg s–1
5. A time dependent force F = 6t acts on a particle of mass 1 kg. If the particle starts from rest,
the work done by the force during the first 1 sec. will be: [JEE(Main)-2017]
(1) 9J (2) 18 J (3) 4.5 J (4) 22 J
6. A particle is moving in a circular path of radius a under the action of an attractive potential energy
k
U=− . Its total energy is: [JEE(Main)-2018]
2r 2
3k k k
(1) − 2
(2) − (3) (4) zero
2a 4a 2 2a2
106 Work, Energy and Power
, 7. A block of mass m, lying on a smooth horizontal surface, is attached to a spring (of negligible
mass) of spring constant k. The other end of the spring is fixed, as shown in the figure. The
block is initially at rest in its equilibrium position. If now the block is pulled with a constant
force F, the maximum speed of the block is: [JEE(Main)-2019]
F 2F F F
(1) (2) (3) (4)
mk mk mk mk
8. A force acts on a 2 kg object so that its position is given as a function of time as x = 3t 2 + 5.
What is the work done by this force in first 5 seconds? [JEE(Main)-2019]
(1) 950 J (2) 875 J (3) 900 J (4) 850 J
9. A block of mass m is kept on a platform which starts from rest with constant acceleration g/2
upward, as shown in fig. Work done by normal reaction on block in time t is: [JEE(Main)-2019]
mg 2 t 2 mg 2t2 3mg 2 t 2
(1) (2) − (3) (4) 0
8 8 8
10. A particle which is experiencing a force, given by F = 3iˆ − 12jˆ , undergoes a displacement of
d = 4iˆ . If the particle had a kinetic energy of 3 J at the beginning of the displacement, what is
its kinetic energy at the end of the displacement? [JEE(Main)-2019]
(1) 9 J (2) 12 J (3) 10 J (4) 15 J
11. A particle moves in one dimension from rest under the influence of a force that varies with the
distance travelled by the particle as shown in the figure. The kinetic energy of the particle after
it has travelled 3 m is [JEE(Main)-2019]
(1) 6.5 J (2) 4 J (3) 2.5 J (4) 5 J
12. A 60 HP electric motor lifts an elevator having a maximum total load capacity of 2000 kg. If the
frictional force on the elevator is 4000 N, the speed of the elevator at full load is close to:
(1 HP = 746 W, g = 10 ms–2) [JEE(Main)-2020]
(1) 1.7 ms–1 (2) 2.0 ms–1 (3) 1.9 ms–1 (4) 1.5 ms–1
Work, Energy and Power 107
1. When a rubber-band is stretched by a distance x, it exerts a restoring force of magnitude
F = ax + bx2 where a and b are constants. The work done in stretching the unstretched rubber
band by L is: [JEE(Main)-2014]
aL2 bL3 1 aL2 bL3
(1)
2
+
3
(2)
2 2
+
3
(3) aL2 + bL3 (4)
1
2
(aL2 + bL3 )
2. A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000
times. Assume that the potential energy lost each time he lowers the mass is dissipated. How
much fat will he use up considering the work done only when the weight is lifted up? Fat
supplies 3.8 × 107 J of energy per kg which is converted to mechanical energy with a 20%
efficiency rate. Take g = 9.8 ms–2. [JEE(Main)-2016]
(1) 12.89 × 10 kg
–3
(2) 2.45 × 10 kg
–3
(3) 6.45 × 10–3 kg (4) 9.89 × 10–3 kg
3. A point particle of mass, moves along the uniformly rough track PQR as shown in the figure.
The coefficient of friction, between the particle and the rough track equals . The particle is
released, from rest, from the point P and it comes to rest at a point R. The energies, lost by the
ball, over the parts, PQ and QR, of the track, are equal to each other, and no energy is lost when
particle changes direction from PQ to QR. The values of the coefficient of friction and the
distance x(= QR) are, respectively close to: [JEE(Main)-2016]
(1) 0.29 and 6.5 m (2) 0.2 and 6.5 m
(3) 0.2 and 3.5 m (4) 0.29 and 3.5 m
4. A body of mass m = 10–2 kg is moving in a medium and experiences a frictional force F = –kv2.
1
Its initial speed is v0 = 10 ms–1. If, after 10 s, its energy is mv02 , the value of k will be:
8
[JEE(Main)-2017]
(1) 10–4 kg m–1 (2) 10–1 kg m–1 s–1
(3) 10–3 kg m–1 (4) 10–3 kg s–1
5. A time dependent force F = 6t acts on a particle of mass 1 kg. If the particle starts from rest,
the work done by the force during the first 1 sec. will be: [JEE(Main)-2017]
(1) 9J (2) 18 J (3) 4.5 J (4) 22 J
6. A particle is moving in a circular path of radius a under the action of an attractive potential energy
k
U=− . Its total energy is: [JEE(Main)-2018]
2r 2
3k k k
(1) − 2
(2) − (3) (4) zero
2a 4a 2 2a2
106 Work, Energy and Power
, 7. A block of mass m, lying on a smooth horizontal surface, is attached to a spring (of negligible
mass) of spring constant k. The other end of the spring is fixed, as shown in the figure. The
block is initially at rest in its equilibrium position. If now the block is pulled with a constant
force F, the maximum speed of the block is: [JEE(Main)-2019]
F 2F F F
(1) (2) (3) (4)
mk mk mk mk
8. A force acts on a 2 kg object so that its position is given as a function of time as x = 3t 2 + 5.
What is the work done by this force in first 5 seconds? [JEE(Main)-2019]
(1) 950 J (2) 875 J (3) 900 J (4) 850 J
9. A block of mass m is kept on a platform which starts from rest with constant acceleration g/2
upward, as shown in fig. Work done by normal reaction on block in time t is: [JEE(Main)-2019]
mg 2 t 2 mg 2t2 3mg 2 t 2
(1) (2) − (3) (4) 0
8 8 8
10. A particle which is experiencing a force, given by F = 3iˆ − 12jˆ , undergoes a displacement of
d = 4iˆ . If the particle had a kinetic energy of 3 J at the beginning of the displacement, what is
its kinetic energy at the end of the displacement? [JEE(Main)-2019]
(1) 9 J (2) 12 J (3) 10 J (4) 15 J
11. A particle moves in one dimension from rest under the influence of a force that varies with the
distance travelled by the particle as shown in the figure. The kinetic energy of the particle after
it has travelled 3 m is [JEE(Main)-2019]
(1) 6.5 J (2) 4 J (3) 2.5 J (4) 5 J
12. A 60 HP electric motor lifts an elevator having a maximum total load capacity of 2000 kg. If the
frictional force on the elevator is 4000 N, the speed of the elevator at full load is close to:
(1 HP = 746 W, g = 10 ms–2) [JEE(Main)-2020]
(1) 1.7 ms–1 (2) 2.0 ms–1 (3) 1.9 ms–1 (4) 1.5 ms–1
Work, Energy and Power 107
