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Free download in PDF Class 11 Physics Chapter 6 Work, Energy and Power Multiple Choice Questions and Answers for Board, JEE, NEET, AIIMS, JIPMER, IIT-JEE, AIEE and other competitive exams. MCQ Questions for Class 11 Physics with Answers were prepared based on the latest exam pattern. These short solved questions or quizzes are provided by Gkseries. These will help the students for preparation of their examination./p>
(1)
What is the ratio of velocities of a nucleus that splits into two parts with radii 1:2
[A]
6:1
[B]
2:1
[C]
8:1
[D]
4:1
(2)
Select the incorrect statement for the given situation: Two bodies with mass m1 and m2 undergo elastic collision
[A]
When m1 and m2 is at rest, the kinetic energy transferred will be maximum
[B]
The bodies will move in the same direction if m1 = m2 and when the collision is in oblique
[C]
When m1 > m2, m2 will move with four times increase in its velocity than m1
[D]
When m1 < m2, the transfer of momentum will be maximum
Answer: When m1 > m2, m2 will move with four times increase in its velocity than m1
(3)
When can one say that work is done on the body
[A]
When the body experiences force
[B]
When there is an increase in energy because of mechanical influence
[C]
When the body moves a certain distance
[D]
None of the above
Answer: When there is an increase in energy because of mechanical influence
(4)
What is the power of the engine when the velocity of the car is v, mass m, acceleration a, and external resistance R
[A]
(R-ma)v
[B]
(R+ma)v
[C]
mav
[D]
Rv
(5)
What is the average power required to lift a mass of 100kg to a height of 50m in 50 seconds?
[A]
980
[B]
100
[C]
50
[D]
5000
(6)
Calculate the final kinetic energy of a block of mass if the mass of the block is 10kg and has a constant velocity of 10m/s. The block of mass is subjected to a retarding force of F=0.1J/m
[A]
275J
[B]
250J
[C]
475J
[D]
450J
(7)
Calculate the energy loss in a perfectly inelastic collision if the mass of the object is 40kg with velocity 4m/s hits the object of mass 60kg with velocity 2m/s.
[A]
440J
[B]
110J
[C]
392J
[D]
48J
(8)
By how much does kinetic energy increase if the momentum is increased by 20%
[A]
55%
[B]
66%
[C]
44%
[D]
77%
(9)
A bullet of mass m fired at 30o to the horizontal leaves the barrel of the gun with a velocity v. The bullet hits a soft target at a height h above the ground while it is moving downward and emerges out with half the kinetic energy it had before hitting the target. Which of the following statements are correct in respect of bullet after it emerges out of the target?
[A]
the velocity of the bullet will be reduced to half its initial value
[B]
the velocity of the bullet will be more than half of its earlier velocity
[C]
the bullet will move in a different parabolic path
[D]
the internal energy of the particles of the target will increase
(10)
A man, of mass m, standing at the bottom of the staircase, of height L, climbs it and stands at its top.
[A]
work done by all forces on man is zero
[B]
work done by all the force on man is zero
[C]
work done by the gravitational force on man is mgL
[D]
the reaction force from a step does not do work because the point of application of the force does not move while the force exists
(11)
A cricket ball of mass 150 g moving with a speed of 126 km/h hits at the middle of the bat, held firmly at its position by the batsman. The ball moves straight back to the bowler after hitting the bat. Assuming that collision between ball and bat is completely elastic and the two remain in contact for 0.001 sec, the force that the batsman had to apply to hold the bat firmly at its place would be
[A]
10.5 N
[B]
21 N
[C]
1.05 × 104 N
[D]
2.1 × 104 N
(12)
In a shotput event an athlete throws the shotput of mass 10 kg with an initial speed of 1 m/s at 45° from height 1.5 m above ground. Assuming air resistance to be negligible and acceleration due to gravity to be 10 m/s2, the kinetic energy of the shotput when it just reaches the ground will be
[A]
2.5 J
[B]
5.0 J
[C]
52.5 J
[D]
155.0 J
(13)
A mass of 5 kg is moving along a circular path of radius 1 m. If the mass moves with 300 revolutions per minute, its kinetic energy would be
[A]
250π2
[B]
100 π2
[C]
5 π2
[D]
0
(14)
A body of mass 0.5 kg travels in a straight line with velocity v = ax3/2 where a = 5 m-1/2s-1. The work done by the net force during its displacement from x = 0 to x = 2 m is
[A]
1.5 J
[B]
50 J
[C]
10 J
[D]
100 J
(15)
During inelastic collision between two bodies, which of the following quantities always remain conserved?
[A]
total kinetic energy
[B]
total mechanical energy
[C]
total linear momentum
[D]
speed of each body
Answer: total linear momentum
(16)
A body is falling freely under the action of gravity alone in a vacuum. Which of the following quantities remain constant during the fall?
[A]
kinetic energy
[B]
potential energy
[C]
total mechanical energy
[D]
total linear momentum
Answer: total mechanical energy
(17)
A bicyclist comes to a skidding stop in 10 m. During this process, the force on the bicyclist due to the road is 200 N and is directly opposed to the motion. The work done by the cycle on the road is
[A]
+2000 J
[B]
-200 J
[C]
zero
[D]
-20,000 J
(18)
A man squatting on the ground gets straight up and stand. The force of reaction of ground on the man during the process is
[A]
constant and equal to mg in magnitude
[B]
constant and greater than mg in magnitude
[C]
variable but always greater than mg
[D]
at first greater than mg, and later becomes equal to mg
Answer: at first greater than mg, and later becomes equal to mg
(19)
A proton is kept at rest. A positively charged particle is released from rest at a distance d in its field. Consider two experiments; one in which the charged particles is also a proton and in another, a positron. In the same time t, the work done on the two moving charged particles is
[A]
the same as the same force law is involved in the two experiments
[B]
less for the case of a positron, as the positron moves away more rapidly and the force on it weakens
[C]
more for the case of a positron, as the positron moves away from a larger distance
[D]
same as the work done by charged particle on the stationary proton
Answer: more for the case of a positron, as the positron moves away from a larger distance
(20)
An electron and a proton are moving under the influence of mutual forces. In calculating the change in the kinetic energy of the system during motion, one ignores the magnetic force of one on another. This is because,
[A]
the two magnetic forces are equal and opposite, so they produce no net effect
[B]
the magnetic forces do no work on each particle
[C]
the magnetic forces do equal and opposite work on each particle
[D]
the magnetic forces are necessarily negligible
Answer: the magnetic forces do no work on each particle
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