JEE Questions for Physics Work Energy And Power Quiz 7 - MCQExams.com

The bob of simple pendulum (mass m and length l) dropped from a horizontal position strike a block of the same mass elastically placed on a horizontal frictionless table. The K.E. of the block will be
  • 2mgl
  • mgl/2
  • mgl
  • zero
A gun fires a bullet of mass 40 g with a velocity of 50 m/s. Because of this the gun is pushed back with a velocity of 1 m/s. The mass of the gun is
  • 1.5 kg
  • 3 kg
  • 2 kg
  • 2.5 kg
If a man increase his speed by 2 m/s, his K.E. is doubled, the original speed of the man is

  • Physics-Work Energy and Power-97823.png
  • 2)
    Physics-Work Energy and Power-97824.png

  • Physics-Work Energy and Power-97825.png

  • Physics-Work Energy and Power-97826.png
The potential energy of a particle varies with distance x as shown in the graph. The force acting on the particle is zero at
Physics-Work Energy and Power-97828.png
  • C
  • B
  • B and C
  • A and D
A body of mass 1.5 kg slide down a curved track which is quadrant of a circle of radius 0.75 meter. All the surfaces are frictionless. If the body starts from rest, its speed at the bottom of the track is ..... ( g = 10 m/s2)
Physics-Work Energy and Power-97830.png
  • 3. 87 m/s
  • 2 m/s
  • 1.5 m/s
  • 0.387 m/s
A body initially at rest undergoes one dimensional motion with constant acceleration. The power delivered to it at time t is proportional to.....
  • t1/2
  • t
  • t3/2
  • t2
An electric motor develops 5 KW of power. How much time will it take to lift a water of mass 100 kg to a height of 20 m ? ( g = 10 m/s2)
  • 4 sec
  • 5 sec
  • 8 sec
  • 10 sec
Bansi does a given amount of work in 30 sec. Jaimeen does the same amount of work... in 15 sec. The ratio of the output power of Bansi to the Jaimeen is....
  • 1:1
  • 1:2
  • 2:1
  • 5:3
A body of mass m is accelerated uniformly from rest to a speed v in time T. The instantaneous power delivered to the body in terms of time is given by.....

  • Physics-Work Energy and Power-97834.png
  • 2)
    Physics-Work Energy and Power-97835.png

  • Physics-Work Energy and Power-97836.png

  • Physics-Work Energy and Power-97837.png
1 kg apple gives 25 KJ energy to a monkey. How much height he can climb by using this energy if his efficiency is 40%. (mass of monkey = 25 kg and g = 10 m/s2)
  • 20m
  • 4m
  • 30m
  • 40m

Physics-Work Energy and Power-97840.png
  • 4W
  • 20 W
  • 21 W
  • 4.2 W

Physics-Work Energy and Power-97842.png
  • 10F1F2M
  • 10(F1 + F2)M
  • (F1 + F2)M
  • Zero
A coolie 2.0 m tall raises a load of 75 kg in 25 from the ground to his head and then walks a distance to 40 m in another 25. The power developed by the coolie is ( g = 10 m/s2)
  • 0.25 kw
  • 0.50 kw
  • 0.75 kw
  • 1.00 kw
A rubber ball is dropped from a height of 5 m on a planet where the acceleration due to gravity is not known. On bouncing, it rises to 1.8 m. The ball losses its velocity on bouncing by a factor of
  • 16/25
  • 9/25
  • 3/5
  • 2/5
Two solid rubber balls P and Q having masses 200 g and 400 g respectively are moving in opposite directions with velocity of P equal to 0.3 m/s. After collision the two balls come to rest, then the velocity of Q is
  • 0.15 m/s
  • 1.5 m/s
  • –0.15 m/s
  • Zero
A sphere collides with another sphere of identical mass. After collision, the two sphere move. The collision is inelastic. Then the angle between the directions of the two spheres is
  • Different from 90o
  • 90o
  • 0o
  • 45o
If a skater of weight 4 kg has initial speed 40 m/s and 2nd one of weight 6 kg has 6 m/s. After collision, they have speed (couple) 6 m/s. Then the loss in K.E. is.....
  • 48 J
  • zero
  • 96 J
  • None of these
A neutron having mass of 1.67 × 10–27 kg and moving at 108 m/s collides with a deutron at rest and sticks to it. If the mass of the deutron is 3.34 × 10–27 kg then the speed of the combination is
  • 3.33 × 107 m/s
  • 3 × 105 m/s
  • 33.3 × 107 m/s
  • 2.98 × 105 m/s
Three identical spherical balls A, B and C are placed on a table as shown in the figure along a straight line. B and C are at rest initially. The ball A hits B head on with a speed of 10 m/s. Then after all collision A and B are brought to rest and C takes off with velocity of...... (elastic collision).
Physics-Work Energy and Power-97847.png
  • 20 m/s
  • 2.5 m/s
  • 10 m/s
  • 7.5 m/s
A billiard ball moving with a speed of 8 m/s collides with an identical ball originally at rest. If the first ball stops after collision, then the second ball will move forward with a speed of..... (elastic collision)
  • 8 m/s
  • 4 m/s
  • 16 m/s
  • 1.0 m/s
Four identical balls are lined in a straight grove made on a horizontal frictionless surface as shown. Two similar balls each moving with a velocity v collide elastically with the row of 4 balls from left. What will happen
Physics-Work Energy and Power-97848.png
  • One ball from the right rolls out with a speed 2v and the remaining balls will remain at rest.
  • Two balls from the right roll out speed v each and the remaining balls will remain statinary.
  • All the four balls in the row will roll out with speed v/4 each and the two colliding balls will come to rest.
  • The colliding balls will come to rest and no ball rolls out from right.
Assertion : The change in kinetic energy of a particle is equal to the work done on it by the net force.
Reason : Change in kinetic energy of particle is equal to the work done only in case of a system of one particle.
  • If both assertion and reason 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 the assertion is true but reason is false.
  • If the assertion and reason both are fare.
Assertion : Work done in moving a body over a closed loop is zero for every force in nature.
Reason : Work done does not depend on nature of force.
  • If both assertion and reason 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 the assertion is true but reason is false.
  • If the assertion and reason both are fare.
Assertion : A weight lifter does no work in holding the weight up.
Reason : Work done is zero because distance moved is zero.
  • If both assertion and reason 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 the assertion is true but reason is false.
  • If the assertion and reason both are fare.
Assertion : Work done by centripetal force is zero.
Reason : This is because centripetal force is always along the tangent.
  • If both assertion and reason 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 the assertion is true but reason is false.
  • If the assertion and reason both are fare.
A force F = kx (where k is positive constant) is acting on a particle. Match column–I and column–II, regarding work done in displacing the particle.
Physics-Work Energy and Power-97849.png
  • a – R, b – P, c – Q
  • a – P, b – Q, c – R
  • a – R, b – Q, c – P
  • a – Q, b – P, c – R
Two vehicles moving on a horizontal road are stopped by same retarding force.
Physics-Work Energy and Power-97850.png
  • a – P, b – Q, c – R, d – S
  • a – Q, b – P, c – S, d – R
  • a – S, b – R, c – Q, d – p
  • a – R, b – S, c – Q, d – P

Physics-Work Energy and Power-97851.png

  • Physics-Work Energy and Power-97852.png
  • 2)
    Physics-Work Energy and Power-97853.png

  • Physics-Work Energy and Power-97854.png
  • 0
Stopping distance of a moving vehicle is directly proportional to
  • Square of the initial velocity
  • Square of the initial acceleration
  • The initial velocity
  • The initial acceleration
  • Mass of the vehicle
When two bodies collide elastically, then
  • Kinetic energy of the system alone is conserved
  • Only momentum is conserved
  • Both energy and momentum are conserved
  • Neither energy nor momentum is conserved
You lift a heavy hook from the floor of the room and keep it in the book-shelf having a height 2 m. In this process you take 5 sec. The work done by you will depend upon
  • Mass of the book and time taken
  • Weight of the book and height of the book-shelf
  • Height of the book-shelf and time taken
  • Mass of the book, height of the book-shelf and time taken
A body of mass m kg is lifted by a man to a height of one meter in 30 sec. Another man lifts the same mass to the same height in 60 sec. The work done by them arc in the ratio
  • 1: 2
  • 1: 1
  • 2 : 1
  • 4 : 1
It is easier to draw up a wooden block along an inclined plane than to haul it vertically, principally because
  • The friction is reduced
  • The mass becomes smaller
  • Only a part of the weight has to be overcome
  • ‘g’ becomes smaller
A force acts on a 30 g particle in such a way that the position of the particle as a function of time is given by x = 3t – 4t2 + t3, where x is in meters and t is in seconds. The work done during the first 4 sec is
  • 5.28 J
  • 450 mJ
  • 490 mJ
  • 530 mJ
A body of mass 10 kg is dropped to the ground from a height of 10 m. The work done by the gravitational force is (g = 9.8 m/s2)
  • –490 J
  • + 490 J
  • –980 J
  • + 980 J
Which of the following is a scalar quantity?
  • Displacement
  • Electric field
  • Acceleration
  • Work
A particle of mass 100 g is thrown vertically upwards with a speed of 5 m/s. The work done by the force of gravity during the time, the particle goes up is
  • –125 J
  • 1.25 J
  • 0.5 J
  • –0.5 J
A force of 5 N acts on a 15 kg body initially at rest. The work done by the force during the first second of motion of the body is
  • 5 J
  • 2)
    Physics-Work Energy and Power-97861.png
  • 6 J
  • 75 J
A force of 5 N, making an angle θ with the horizontal, acting on an object displaces it by 0.4 m along the horizontal direction. If the object gains kinetic energy of 1J, the horizontal component of the force is
  • 1.5 N
  • 2.5 N
  • 3.5 N
  • 4.5 N
The work done against gravity in taking 10 kg mass at 1m height in 1sec will be
  • None of these
  • 49 J
  • 98 J
  • 196 J
The energy which an e– acquires when accelerated through a potential difference of 1 volt is called
  • 1 Joule
  • 1 eV
  • 1 Erg
  • 1 Watt
A body of mass 10 kg at rest is acted upon simultaneously by two forces 4 N and 3 N at right angles to each other. The kinetic energy of the body at the end of 10 sec is
  • 100 J
  • 300 J
  • 50 J
  • 125 J
A man starts walking from a point on the surface of Earth (assumed smooth) and reaches diagonally opposite point. What is the work done by him?
  • Zero
  • Positive
  • Negative
  • Nothing can be said
The kinetic energy acquired by a body of mass m in travelling some distance s, starting from rest under the action of a constant force, is directly proportional to
  • mo
  • m
  • m2
  • √m
A ball of mass m moves with speed v and strikes a wall having infinite mass and it returns with same speed, then the work done by the ball on the wall is
  • zero
  • mv J
  • m/v J
  • v/m J
A ball is released from the top of a tower. The ratio of work done by force of gravity in first, second and third second of the motion of the ball is
  • 1 : 2 : 3
  • 1 : 4 : 9
  • 1 : 3 : 5
  • 1 : 5 : 3
A body of mass 5 kg is placed at the origin and can move only on the x-axis. A force of 10 N is acting on it in a direction making an angle of 60° with the x-axis and displaces it along the x-axis by 4 m. The work done by the force is
  • 2.5 J
  • 7.25 J
  • 40 J
  • 20 J
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
  • Its velocity is constant
  • Its acceleration is constant
  • Its kinetic energy is constant
  • It moves in a straight line
Two bodies of masses 1 kg and 5 kg 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 block of mass 5 kg is resting on a smooth surface. At what angle a force of 20 N be acted on the body so that it will acquired a kinetic energy of 40 J after moving 4m
  • 30o
  • 45o
  • 60o
  • 120o
0:0:1


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