JEE Questions for Physics Work Energy And Power Quiz 12 - MCQExams.com

Assertion Power developed in circular motion is always zero.
Reason Work done in case of circular motion is zero.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
Assertion Kinetic energy of a body is quadrupled, when its velocity is doubled.
Reason Kinetic energy is proportional to square of velocity.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
Assertion A quick collision between two bodies is more violent than slow collision, even when initial and final velocities are identical.
Reason The rate of change of momentum determines that force is small or large
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
Assertion Work done by or against gravitational force in moving a body from one point to another is independent of the actual path followed between the two points.
Reason Gravitational forces are conservation forces.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
Assertion Wire through which current flows gets heated.
Reason When current is drawn from a cell, chemical energy is converted into heat energy.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
Assertion Graph between potential energy of a spring versus the extension or compression of the spring is a straight line.
Reason Potential energy of a stretched or compressed spring, proportional to square of extension or compression.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
Assertion Heavy water is used as moderator in nuclear reactor.
Reason Water cools down the fast neutrons.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
A horizontal force of 5 N is required to maintain a velocity of 2 m/s for a block of 10 kg mass sliding over a rough surface. The work done by this force in one minute is
  • 600 J
  • 60 J
  • 6 J
  • 6000 J
Work done in time t on a body of mass m which is accelerated from rest to a speed v in time t1 as a function of time t is given by

  • Physics-Work Energy and Power-98349.png
  • 2)
    Physics-Work Energy and Power-98350.png

  • Physics-Work Energy and Power-98351.png

  • Physics-Work Energy and Power-98352.png
When a body moves with some friction on a surface
  • It loses kinetic energy but momentum is constant
  • It loses kinetic energy but gains potential energy
  • Kinetic energy and momentum both decrease
  • Mechanical energy is conserved
A bullet of mass m moving with velocity v strikes a suspended wooden block of mass M. If the block rises to a height h, the initial velocity of the block will be

  • Physics-Work Energy and Power-98354.png
  • 2)
    Physics-Work Energy and Power-98355.png

  • Physics-Work Energy and Power-98356.png

  • Physics-Work Energy and Power-98357.png
A nucleus at rest splits into two nuclear parts having same density and radii in the ratio 1: 2. Their velocities are in the ratio
  • 2 : 1
  • 4 : 1
  • 6 : 1
  • 8 : 1
The slope of kinetic energy displacement curve of a particle in motion is
  • Equal to the acceleration of the particle
  • Inversely proportional to the acceleration
  • Directly proportional to the acceleration
  • None of the above
A body of mass 2 kg slides down a curved track which is quadrant of a circle of radius 1 m. All the surfaces are frictionless. if the body starts from rest, its speed at the bottom of the track is
Physics-Work Energy and Power-98362.png
  • 4.43 m/sec
  • 2 m/sec
  • 0.5 m/sec
  • 19.6 m/sec
A ball moving with speed v hits another identical ball at rest. The two balls stick together after collision. If specific heat of the material of the balls is S, the temperature rise resulting from the collision is

  • Physics-Work Energy and Power-98363.png
  • 2)
    Physics-Work Energy and Power-98364.png

  • Physics-Work Energy and Power-98365.png

  • Physics-Work Energy and Power-98366.png
A bomb of mass 3 m kg explodes into two pieces of mass m kg and 2 m kg. If the velocity of m kg mass is 16 m/s. the total kinetic energy released in the explosion is
  • 192 mJ
  • 96 mJ
  • 384 mJ
  • 768 mJ
Which one of the following statement does not hold good when two balls of masses m1 and m2 undergo elastic collision
  • When m1 << m2 and m2 at rest, there will be maximum transfer of momentum
  • When m1 >> m2 and m2 at rest, after collision the ball of mass m2 moves with four times the velocity of
  • When m1 = m2 and m2 at rest, there will be maximum transfer of K.E.
  • When collision is oblique and m2 at rest with m1 = m2, after collision the balls move in opposite directions
A neutron travelling with a velocity v and K.E. E collides perfectly elastically head on with the nucleus of an atom of mass number A at rest. The fraction of total energy retained by neutron is

  • Physics-Work Energy and Power-98369.png
  • 2)
    Physics-Work Energy and Power-98370.png

  • Physics-Work Energy and Power-98371.png

  • Physics-Work Energy and Power-98372.png

Physics-Work Energy and Power-98374.png
  • 0.75
  • 1.33
  • 3.0
  • 4.0
Six identical balls are lined in a straight groove made on a horizontal frictionless surface as shown. Two similar balls each moving with a velocity v collide elastically with the row of 6 balls from left. What will happen
Physics-Work Energy and Power-98376.png
  • One ball from the right rolls out with a speed 2v and the remaining balls will remains at rest
  • Two ball from the right roll will out with speed v each and the remaining balls will remain stationary
  • All the six balls in the row will roll out with speed v/6 each and the two colliding balls will come to rest
  • The colliding balls will come to rest and no ball roll out from right.
A wooden block of mass M rests on a horizontal surface. A bullet of mass m moving in the horizontal direction strikes and gets embedded in it. The combined system covers a distance x on the surface. If the coefficient of friction between wood and the surface is μ, the speed of the bullet at the time of striking the block is (where m is mass of the bullet)

  • Physics-Work Energy and Power-98377.png
  • 2)
    Physics-Work Energy and Power-98378.png

  • Physics-Work Energy and Power-98379.png

  • Physics-Work Energy and Power-98380.png
Identify the false statement from the following
  • Work-energy theorem is not independent of Newton’s second law.
  • Work-energy theorem holds in all inertial frames
  • Work done by friction over a closed path is zero
  • No potential energy can be associated with friction
  • Work done is a scalar quantity
Stopping distance of a moving vehicle is directly proportional to
  • Square of the initial velocity
  • Square of the initial acceleration
  • The initial acceleration
  • Mass of the vehicle
A body moves a distance of 10 m along a straight line under the action of a force 5 N. if the work done is 25 joules, the angle which the force makes with the direction of motion of the body is
  • 0o
  • 30o
  • 60o
  • 90o
The work done in pulling up a block of wood weighing 2kN for a length 10 m on a smooth plane inclined at an angle of 15° with the horizontal is [sin 15° = 0.2588]
  • 4.36 kJ
  • 5.17 kJ
  • 8.91 kJ
  • 9.82 kJ
The area of the acceleration-displacement curve of a body gives
  • Impulse
  • Change in momentum per unit mass
  • Change in KE per unit mass
  • Total change in energy
A cylinder of mass 10 kg is sliding on a plane with an initial velocity of 10 m/s. If coefficient of friction between surface and cylinder is 0.5, then before stopping it will describe
  • 12.5 m
  • 5 m
  • 7.5 m
  • 10 m
Two bodies of masses 1kg and 5kg are dropped gently from the top of a tower. At a point 20 cm from the ground, both the bodies will have the same
  • Momentum
  • Kinetic energy
  • Velocity
  • Total energy
A cord is used to lower vertically a block of mass M by a distance d with constant downward acceleration g/4.Work done by the cord on the block is

  • Physics-Work Energy and Power-98387.png
  • 2)
    Physics-Work Energy and Power-98388.png

  • Physics-Work Energy and Power-98389.png

  • Physics-Work Energy and Power-98390.png
The potential energy of a certain spring when stretched through a distance \'S\' is 10 joule. The amount of work (in joule) that must be done on this spring to stretch it through an additional distance \'S\' will be
  • 30
  • 40
  • 10
  • 20
Two springs of spring constants 1500 N/m and 3000 N/m respectively are stretched with the same force. They will have potential energy in the ratio
  • 4 : 1
  • 1 : 4
  • 2 : 1
  • 1 : 2
A spring 40 mm long is stretched by the application of a force. If 10 N force required to stretch the spring through 1 mm, then work done in stretching the spring through 40 mm is
  • 84 J
  • 68 J
  • 23 J
  • 8 J
A body of mass 3 kg is under a force, which causes a displacement in it given by S = t3/3 (in m). Find the work done by the force in first 2 seconds
  • 2 J
  • 3.8 J
  • 5.2 J
  • 24 J
The force constant of a wire is k and that of another wire is 2k. When both the wires are stretched through same distance, then the work done

  • Physics-Work Energy and Power-98396.png
  • W2 = 2W1
  • W2 = W1
  • W2 = 0.5 W1
A body of mass 0.1 kg moving with a velocity of 10 m/s hits a spring (fixed at the other end) of force constant 1000 N/m and comes to rest after compressing the spring. The compression of the spring is
  • 0.01 m
  • 0.1 m
  • 0.2 m
  • 0.5 m
A mass of 0.5 kg moving with a speed of 1.5 m/s on a horizontal smooth surface, collides with a nearly weightless spring of force constant k = 50 N/m. The maximum compression of the spring would be
  • 0.15 m
  • 0.12 m
  • 1.5 m
  • 0.5 m
A spring with spring constant k when stretched through 1cm, the potential energy is U. If it is stretched by 4 cm. The potential energy will be
  • 4U
  • 8U
  • 16U
  • 2U
A spring with spring constant k is extended from x = a to x = x1. The work done will be

  • Physics-Work Energy and Power-98401.png
  • 2)
    Physics-Work Energy and Power-98402.png

  • Physics-Work Energy and Power-98403.png

  • Physics-Work Energy and Power-98404.png
If a long spring is stretched by 0.02 m, its potential is U. If the spring is stretched by 0.1 m, then its potential energy will be
  • U/5
  • U
  • 5U
  • 25U
The spring extends by x on loading, then energy stored by the spring is (if T is the tension in spring and k is spring constant)

  • Physics-Work Energy and Power-98406.png
  • 2)
    Physics-Work Energy and Power-98407.png

  • Physics-Work Energy and Power-98408.png

  • Physics-Work Energy and Power-98409.png

Physics-Work Energy and Power-98411.png
  • 360 J
  • 240 J
  • – 240 J
  • – 360 J

Physics-Work Energy and Power-98413.png
  • – 7 J
  • Zero
  • + 7 J
  • + 19 J

Physics-Work Energy and Power-98415.png
  • B/2A
  • 2A/B
  • A/B
  • B/A
A body of mass m accelerates uniformly from rest v1 in time t1. As a function of time t, the instantaneous power delivered to the body is

  • Physics-Work Energy and Power-98417.png
  • 2)
    Physics-Work Energy and Power-98418.png

  • Physics-Work Energy and Power-98419.png

  • Physics-Work Energy and Power-98420.png
Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional forces are 10% of energy. How much power is generated by the turbine (g = 10 m/s2)
  • 12.3 kW
  • 7.0 kW
  • 8.1 kW
  • 10.2 kW
An electric immersion heater of 1.08 kW is immersed in water. After the water has reached a temperature of 100°C, how much time will be required to produce 100g of steam
  • 210 s
  • 105 s
  • 420 s
  • 50 s
Power of a water pump is 2 kW. If g = 10 m/sec2, the amount of water it can raise in one minute to a height of 10 m is
  • 2000 litre
  • 1000 litre
  • 100 litre
  • 1200 litre
An engine develops 10 kW of power. How much time will it take to lift a mass of 200 kg to a height of 40 m. (g = 10 m/sec2)
  • 4 sec
  • 5 sec
  • 8 sec
  • 10 sec
An apple give 21 kJ energy to a boy. How much height he can climb by using the energy if his efficiency is 28% (mass of by = 40 kg)
  • 15 m
  • 10 m
  • 5 m
  • 22.5 m
The power of a pump, which can pump 200 kg of water to a height of 200 m in 10 sec is (g = 10 m/sec2)
  • 40 kW
  • 80 kW
  • 400 kW
  • 960 kW
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