JEE Questions for Physics Work Energy And Power Quiz 1 - MCQExams.com

For inelastic collision between two spherical rigid bodies
  • the total kinetic energy is conserved
  • the total mechanical energy is not conserved
  • the linear momentum is not conserved
  • the linear momentum is conserved
A ball is dropped from height 20 m. If coefficient of restitution is 0.9, what will be the height attained after first bounce?
  • 1.62 m
  • 16.2 m
  • 18 m
  • 14 m
A piece of wire is bent in the shape of a parabola y = kx2 (y-axis vertical) with a bead of mass m on it. The bead can slide on the wire without friction. It stays at the lowest point of the parabola when the wire is at rest. The wire is now accelerated parallel to the x-axis with a constant acceleration a. The distance of the new equilibrium position of the bead, where the bead can stay at rest with respect to the wire, from the y-axis is

  • Physics-Work Energy and Power-97295.png
  • 2)
    Physics-Work Energy and Power-97296.png

  • Physics-Work Energy and Power-97297.png

  • Physics-Work Energy and Power-97298.png
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
  • aL2 + bL3
  • 2)
    Physics-Work Energy and Power-97300.png

  • Physics-Work Energy and Power-97301.png

  • Physics-Work Energy and Power-97302.png
A block of mass 2 kg is free to move along the x-axis. It is at rest and from t = 0 onwards it is subjected to a time-dependent force F(t) in the x direction. The force F(t) varies with t as shown in the figure. The kinetic energy of the block after 4.5 seconds is
Physics-Work Energy and Power-97304.png
  • 4.50 J
  • 7.50 J
  • 5.06 J
  • 14.06 J
A spring stores 1 J of energy for a compression of 1 mm. The additional work to be done to compress it further by 1 mm is
  • 1 J
  • 2 J
  • 3 J
  • 4 J
  • 0.5 J
Force of 50 N acting on a body at an angle θ with horizontal. If 150 J work is done by displacing it 3 m, then θ is
  • 60°
  • 30°
  • 0°
  • 45°

Physics-Work Energy and Power-97308.png

  • Physics-Work Energy and Power-97309.png
  • 2)
    Physics-Work Energy and Power-97310.png

  • Physics-Work Energy and Power-97311.png
  • 0
If W1, W2 and W3 are the work done in moving a particle from A and B along three different paths 1, 2 and 3 respectively (as shown) in the gravitational field of a point mass M, the relation between W1, W2 and W3 is
Physics-Work Energy and Power-97313.png
  • W1 > W2 > W3
  • W1 = W2 = W3
  • W1 < W2 < W3
  • W2 > W1 > W3
A spring of force-constant k is cut into two pieces such that one piece is double the length of the other. Then the long piece will have a force-constant of

  • Physics-Work Energy and Power-97314.png
  • 2)
    Physics-Work Energy and Power-97315.png

  • Physics-Work Energy and Power-97316.png

  • Physics-Work Energy and Power-97317.png
The work done by a force acting on a body is as shown in the graph. The total work done in covering an initial distance of 20 m is
Physics-Work Energy and Power-97318.png
  • 225 J
  • 200 J
  • 400 J
  • 175 J
A tennis ball is dropped on a horizontal smooth surface. It bounces back to its original position after hitting the surface. The force on the ball during the collision is proportional to the length of compression of the ball. Which one of the following sketches describes the variation of its kinetic energy K with time t most appropriately? The figure are only illustrative and not to the scale.

  • Physics-Work Energy and Power-97320.png
  • 2)
    Physics-Work Energy and Power-97321.png

  • Physics-Work Energy and Power-97322.png

  • Physics-Work Energy and Power-97323.png
A force of (5 + 3x )N acting on a body of mass 20 kg, along the x-axis displaces it from x = 2 m to x = 6 m. The work done by the force is
  • 20 J
  • 48 J
  • 68 J
  • 86 J
A spring which is initially in its unstretched condition, is first stretched by a length x and then again by a further length x. The work done in the first case is W1 and in the second case is W2. Then
  • W2 = W1
  • W2 = 2W1
  • W2 = 3W1
  • W2 = 4W1
Which of the following statements are incorrect?
I. If there were no friction, work need to be done to move a body up an inclined plane is zero.
II. If there were no friction, moving vehicles could not be stopped even by locking the brakes.
III. As the angle of inclination is increased, the normal reaction on the body placed on it increases.
IV. A duster weighing 0.5 kg is pressed against a vertical board with a force of 11 N. If the coefficient of friction is 0.5, the work done in rubbing it upward through a distance of 10 cm is 0.55 J.
  • I and II
  • I , II and IV
  • I , III and IV
  • None of these
The area under the displacement–force curve gives
  • distance travelled
  • total force
  • momentum
  • work done
4 m3 of water is to be pumped to a height of 20 m and forced into a reservoir at a pressure of 2 x 105 Nm-2. The work done by the motor is (given, external pressure =105 Nm-2)
  • 8 × 105 J
  • 16 × 105 J
  • 12 × 105 J
  • 32 × 105 J

Physics-Work Energy and Power-97329.png
  • 8.7 ×10-2 J
  • 12.2 ×10-2 J
  • 8.7 ×10-1 J
  • 12.2 ×10-1 J

Physics-Work Energy and Power-97331.png

  • Physics-Work Energy and Power-97332.png
  • 2)
    Physics-Work Energy and Power-97333.png

  • Physics-Work Energy and Power-97334.png

  • Physics-Work Energy and Power-97335.png

Physics-Work Energy and Power-97337.png
  • 100 J
  • 150 J
  • 120 J
  • 200 J

Physics-Work Energy and Power-97339.png
  • 57 J
  • 58 J
  • 59 J
  • 60 J
A spring of spring constant 5 x 103 Nm-1 is stretched initially by 5 cm from the unstretched position. Then the work required to stretch it further by another 5 cm is
  • 12.50 N–m
  • 18.75 N–m
  • 25 N–m
  • 6.25 N–m
A rod AB of mass 10 kg and length 4 m rests on a horizontal floor with end A fixed so, as to rotate it in vertical plane about perpendicular axis passing through A. If the work done on the rod is 100 J, the height to which the end B be raised vertically above the floor is
  • 1.5 m
  • 2 m
  • 1 m
  • 2.5 m
  • 3 m
When a force is applied on a moving body, its motion is retarded. Then, the work done is
  • positive
  • negative
  • zero
  • positive and negative
A body moves a distance of 10 m along a straight line under a action of 5 N force. If work done is 25 J, then angle between the force and direction of motion of the body will be
  • 75°
  • 60°
  • 45°
  • 30°
A mass of M kg is suspended by a weightless string. The horizontal force that is required to displace it until the string makes an angle of 45° with the initial vertical direction is

  • Physics-Work Energy and Power-97345.png
  • 2)
    Physics-Work Energy and Power-97346.png

  • Physics-Work Energy and Power-97347.png

  • Physics-Work Energy and Power-97348.png
A particle of mass 100 g is thrown vertically upwards with a speed of 5 ms-1. The work done by the force of gravity during the time, the particle goes up is
  • –0.5 J
  • –1.25 J
  • 1.25 J
  • 0.5 J
An ideal spring with spring-constant k is hung from the ceiling and a block of mass M is attached to its lower end. The mass is released with the spring initially unstretched. Then the maximum extension in the spring is

  • Physics-Work Energy and Power-97351.png
  • 2)
    Physics-Work Energy and Power-97352.png

  • Physics-Work Energy and Power-97353.png

  • Physics-Work Energy and Power-97354.png

Physics-Work Energy and Power-97356.png

  • Physics-Work Energy and Power-97357.png
  • 2)
    Physics-Work Energy and Power-97358.png

  • Physics-Work Energy and Power-97359.png

  • Physics-Work Energy and Power-97360.png
A bullet of mass 10 g is fired horizontally with a velocity 1000 ms-1 from a rifle situated at a height 50 m above the ground. If the bullet reaches the ground with a velocity 500 ms-1, the work done against air resistance in the trajectory of the bullet is (take g = 10 m-2)
  • 5005 J
  • 3755 J
  • 3750 J
  • 17.5 J
A spring of force constant 800 Nm-1 has an extension of 5cm. The work done in extending it from 5 cm to 15 cm is
  • 16 J
  • 8 J
  • 32 J
  • 24 J
A particle which is constrained to move along the x-axis, is subjected to a force in the same direction which varies with the distance x of the particle from the origin is F (x) = – kx + ax3 . Here, k and a are positive constants. For x ≥ 0, the functional form of the potential energy U(x) of the particle is

  • Physics-Work Energy and Power-97363.png
  • 2)
    Physics-Work Energy and Power-97364.png

  • Physics-Work Energy and Power-97365.png

  • Physics-Work Energy and Power-97366.png
A particle of mass 2 mg moves with constant speed and is found to pass two points 5.0 m apart in a time interval of 5 ms. Find the kinetic energy of the particle
  • 1 J
  • 2 J
  • 3 J
  • 4 J

Physics-Work Energy and Power-97369.png

  • Physics-Work Energy and Power-97370.png
  • 2)
    Physics-Work Energy and Power-97371.png

  • Physics-Work Energy and Power-97372.png

  • Physics-Work Energy and Power-97373.png
A cannon shell fired breaks into two equal parts at its highest point. One part retraces the path to the cannon with kinetic energy E1 and kinetic energy of the second part is E2, relation between E1 and E2 is
  • E2 = 15 E1
  • E2 = E1
  • E2 = 4 E1
  • E2 = 9 E1
A shell of mass 20 kg at rest explodes into two fragments whose masses are in the ratio 2 : 3. The smaller fragment moves with a velocity of 6 ms-1. The kinetic energy of the larger fragment is
  • 96 J
  • 216 J
  • 144 J
  • 360 J
The magnitude of momentum of particle is increased by 100%. The increase in its kinetic energy is
  • 100%
  • 200%
  • 300%
  • 400%
A particle of mass 4m which is at rest explodes into three fragments. Two of the fragments each of mass m are found to move with a speed v each mutually perpendicular directions. The total energy released in this process is
  • 0
  • 2)
    Physics-Work Energy and Power-97378.png

  • Physics-Work Energy and Power-97379.png

  • Physics-Work Energy and Power-97380.png
Potential energy of a particle is to α coordinate by equation x2 – 2x will be equilibrium at
  • x = 0.5
  • x = 2
  • x = 1
  • x = 4
Two bodies of masses m1 and m2 are acted upon by constant force F for a time t. They start from rest and acquire kinetic energies E1 and E2, respectively. Then, E1/E2 is

  • Physics-Work Energy and Power-97383.png
  • 2)
    Physics-Work Energy and Power-97384.png

  • Physics-Work Energy and Power-97385.png
  • 1
A body of mass 5 kg is thrown vertically up with a kinetic energy of 490 J. The height at which the kinetic energy of the body becomes half of the original value is
  • 12.5 m
  • 10 m
  • 2.5 m
  • 5 m
A ball dropped from a height of 2 m rebounds to a height of 1.5 m after hitting the ground. Then, the percentage of energy lost is
  • 25
  • 30
  • 50
  • 100
A particle is projected from the ground with a kinetic energy E at an angle of 60° with the horizontal. Its kinetic energy at the highest point of its motion will be

  • Physics-Work Energy and Power-97389.png
  • E/2
  • E/4
  • E/8
A cubical vessel of height 1 m is full of water. What is the amount of work done in pumping water out of the vessel? (take, g =10 ms-2)
  • 1250 J
  • 5000 J
  • 1000 J
  • 2500 J

Physics-Work Energy and Power-97392.png
  • 12 J
  • 9 J
  • 6 J
  • 3 J
Two balls of masses 2 g and 6 g are moving with kinetic energy in the ratio of 3 : 1. What is the ratio of their linear momenta?
  • 1 : 1
  • 2 : 1
  • 1 : 2
  • None of these
If the kinetic energy of a body is increased two times, its momentum will
  • half
  • remain unchanged
  • be doubled

  • Physics-Work Energy and Power-97395.png
A 16 kg block moving on a frictionless horizontal surface with a velocity of 4 m/s compresses an ideal spring and comes to rest. If the force constant of the spring be 100 N/m, then the spring is compressed by
  • 1.6 m
  • 4 m
  • 6.1 m
  • 3.2 m
A bomb of mass 30 kg at rest explodes into two pieces of masses 18 kg and 12 kg. The velocity of 18 kg mass is 6 ms-1. The kinetic energy of the other mass is
  • 256 J
  • 486 J
  • 524 J
  • 324 J
Which of the following statements is wrong?
  • KE of a body is independent of the direction of motion.
  • In an elastic collision of two bodies, the momentum and energy of each body is conserved.
  • If two protons are brought towards each other the potential energy of the system decreases.
  • A body cannot have energy without momentum.
0:0:1


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