JEE Questions for Physics Work Energy And Power Quiz 9 - MCQExams.com

A 2 kg block slides on a horizontal floor with a speed of 4 m/s. It strikes an uncompressed spring and compresses it till the block is motionless. The kinetic friction force is 1.5 N and spring constant is 10,000 N/m. The spring compresses by
  • 5.5 cm
  • 2.5 cm
  • 11.0 cm
  • 8.5 cm
A bullet moving with a speed of 100 ms–1 can just penetrate two planks of equal thickness. Then, the number of such planks penetrated by the same bullet when the speed is doubled will be
  • 4
  • 8
  • 6
  • 10
If momentum is increased by 20%, then kinetic energy increases by
  • 48%
  • 44%
  • 40%
  • 36%
The energy associated with one gram of mass is

  • Physics-Work Energy and Power-97985.png
  • 2)
    Physics-Work Energy and Power-97986.png

  • Physics-Work Energy and Power-97987.png

  • Physics-Work Energy and Power-97988.png
A body of mass m accelerates uniformly from rest to v1 in time t1. As a function of time t, the instantaneous power delivered to the body is

  • Physics-Work Energy and Power-97989.png
  • 2)
    Physics-Work Energy and Power-97990.png

  • Physics-Work Energy and Power-97991.png

  • Physics-Work Energy and Power-97992.png
An electric pump is used to fill an overhead tank of capacity 9 m3 kept at a height of 10 m above the ground. If the pump takes 5 mm to fill the tank by consuming 10 kW power the efficiency of the pump should be (Take g = 10 ms–2)
  • 60%
  • 40%
  • 20%
  • 30%
A body of mass 2 kg is projected at 20 m/s at an angle 60° above the horizontal. Power on the block due to the gravitational force at its highest point is
  • 200 W
  • 2)
    Physics-Work Energy and Power-97995.png
  • 50 W
  • zero
A body is initially at rest. It undergoes one-dimensional motion with constant acceleration. The power delivered to it at time t is proportional to

  • Physics-Work Energy and Power-97997.png
  • 2)
    Physics-Work Energy and Power-97998.png

  • Physics-Work Energy and Power-97999.png

  • Physics-Work Energy and Power-98000.png
From a waterfall, water is falling down at the rate of 100 kg/s on the blades of turbine. If the height of the fall is 100 m, then the power delivered to the turbine is approximately equal to
  • 100 kW
  • 10 kW
  • 1 kW
  • 1000 kW
A 10 H.P. motor pumps out water from a well of depth 20 m and fills a water tank of volume 22380 litres at a height of 10 m from the ground. The running time of the motor to fill the empty water tank is (g = 10 m sec–2)
  • 5 min
  • 10 min
  • 15 min
  • 20 min
A car of mass 1250 kg is moving at 30 m/s. Its engine delivers 30 kW while resistive force due to surface is 750 N. What maximum acceleration can be given in the car?

  • Physics-Work Energy and Power-98004.png
  • 2)
    Physics-Work Energy and Power-98005.png

  • Physics-Work Energy and Power-98006.png

  • Physics-Work Energy and Power-98007.png
A truck of mass 30,000 kg moves up an inclined plane of slope 1 in 100 at a speed of 30 kmph. The power of the truck is (Given g = 10 m sec–2)
  • 25 kW
  • 10 kW
  • 5 kW
  • 2.5 kW
A 60 kg man runs up a staircase in 12 sec while a 50 kg man runs up the same staircase in 11 sec. The ratio of the rate of doing their work is
  • 6 : 5
  • 12 : 11
  • 11 : 10
  • 10 : 11
A man does a given amount of work in 10 sec. Another man does the same amount of work in 20 sec. The ratio of the output power of first man to the second man is
  • 1
  • 1/2
  • 2/1
  • None of these
A car of mass 1000 kg accelerates uniformly from rest to a velocity of 54 km/hr in 5s. The average power of the engine during this period in watts is (neglect friction)
  • 2000 W
  • 22500 W
  • 5000 W
  • 2250 W
A quarter horse power motor runs at a speed of 600 r.p.m. Assuming 40% efficiency the work done by the motor in one rotation will b
  • 7.46 J
  • 7400 J
  • 7.46 ergs
  • 74.6 J
From an automatic gun a man fires 360 bullet per minute with a speed of 360 km/hr. If each weights 20 g, the power of the gun is
  • 600 W
  • 300 W
  • 150 W
  • 75 W
An engine pump is used to pump a liquid of density p continuously through a pipe of cross-sectional area A. If the speed of flow of the liquid in the pipe is v, then the rate at which kinetic energy is being imparted to the liquid is

  • Physics-Work Energy and Power-98015.png
  • 2)
    Physics-Work Energy and Power-98016.png

  • Physics-Work Energy and Power-98017.png

  • Physics-Work Energy and Power-98018.png
If the heart pushes 1 cc of blood in one second under pressure 20000 N/m2, the power of heart is
  • 0.02 W
  • 400 W

  • Physics-Work Energy and Power-98020.png
  • 0.2 W
A body of mass M is moving with a uniform speed of 10 m/s on frictionless surface under the influence of two forces F1 and F2. The net power of the system is
Physics-Work Energy and Power-98022.png

  • Physics-Work Energy and Power-98023.png
  • 2)
    Physics-Work Energy and Power-98024.png

  • Physics-Work Energy and Power-98025.png
  • Zero

Physics-Work Energy and Power-98027.png
  • 4 W
  • 5 W
  • 2 W
  • 8 W
  • 1 W
The coefficient of restitution e for a perfectly elastic collision is
  • 1
  • 0
  • ∞
  • –1
Three objects A, B and C are kept in a straight line on a frictionless horizontal surface. These have masses m, 2m and m, respectively. The object A moves towards B with a speed 9 m/s and makes an elastic collision with it. Thereafter, B makes completely inelastic collision with C. All motions occur on the same straight line. Find the final speed (in m/s) of the object C.
Physics-Work Energy and Power-98029.png
  • 3 m/s
  • 4 m/s
  • 5 m/s
  • 1 m/s
A sphere of mass m moving with a constant velocity u hits another stationary sphere of the same mass. If e is the coefficient of restitution, then the ratio of the velocity of two spheres after collision will be

  • Physics-Work Energy and Power-98031.png
  • 2)
    Physics-Work Energy and Power-98032.png

  • Physics-Work Energy and Power-98033.png

  • Physics-Work Energy and Power-98034.png
Two solid rubber balls A and B having masses 200 and 400 g respectively are moving in opposite directions with velocity of A equal to 0.3 m/s. After collision the two halls come to rest, then the velocity of B is
  • 0.15 m/sec
  • 1.5 m/sec
  • –0.15 m/sec
  • None of these
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
A canon ball is fired with a velocity 200 m/sec at an angle of 60o with the horizontal. At the highest point of its flight it explodes into 3 equal fragments, one going vertically upwards with a velocity 100 m/sec, the second one falling vertically downwards with a velocity 100 m/sec. The third fragment will be moving with a velocity
  • 100 m/s in the horizontal direction
  • 300 m/s in the horizontal direction
  • 300 m/s in a direction making an angle of 60° with the horizontal
  • 200 m/s in a direction making an angle of 60° with the horizontal
A lead hail strikes a wall and falls down, a tennis ball having the same mass and velocity strikes the wall and bounces back. Check the correct statement
  • The momentum of the lead ball is greater than that of the tennis ball
  • The lead ball suffers a greater change in momentum compared with the tennis ball
  • The tennis ball suffers a greater change in momentum as compared with the lead ball
  • Both suffer an equal change in momentum
An intense stream of water of cross-sectional area A strikes a wall at an angle θ with the normal to the wall and returns back elastically. If the density of water is ρ and its velocity is v, then the force exerted in the wall will be
Physics-Work Energy and Power-98039.png

  • Physics-Work Energy and Power-98040.png
  • 2)
    Physics-Work Energy and Power-98041.png

  • Physics-Work Energy and Power-98042.png

  • Physics-Work Energy and Power-98043.png
A sphere collides with another sphere of identical mass. After collision, the two spheres move. The collision is inelastic. Then, the angle between the directions of the two spheres is
  • 90o
  • 0o
  • 45o
  • Different from 90o
A 238U nucleus decays by emitting an alpha particle of speed v ms–1. The recoil speed of the residual nucleus is (in ms–1)
  • –4v/234
  • v/4
  • –4v/238
  • 4v/238
A smooth sphere of mass M moving with velocity u directly collides elastically with another sphere of mass in at rest. After collision their final velocities are V and v respectively. The value of u is

  • Physics-Work Energy and Power-98046.png
  • 2)
    Physics-Work Energy and Power-98047.png

  • Physics-Work Energy and Power-98048.png

  • Physics-Work Energy and Power-98049.png
A body of mass m having an initial velocity v, makes head on collision with a stationary body of mass M. After the collision, the body of mass m comes to rest and only the body having mass M moves. This will happen only when

  • Physics-Work Energy and Power-98051.png
  • 2)
    Physics-Work Energy and Power-98052.png

  • Physics-Work Energy and Power-98053.png

  • Physics-Work Energy and Power-98054.png

Physics-Work Energy and Power-98055.png

  • Physics-Work Energy and Power-98056.png
  • 2)
    Physics-Work Energy and Power-98057.png

  • Physics-Work Energy and Power-98058.png
  • zero
A shell of mass m moving with velocity v suddenly breaks into 2 pieces. The part having mass m/4 remains stationary. The velocity of the other shell will be
  • v
  • 2v

  • Physics-Work Energy and Power-98059.png

  • Physics-Work Energy and Power-98060.png
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 loses its velocity on bouncing by a factor of
  • 16/25
  • 2/5
  • 3/5
  • 9/25

Physics-Work Energy and Power-98063.png

  • Physics-Work Energy and Power-98064.png
  • 2)
    Physics-Work Energy and Power-98065.png

  • Physics-Work Energy and Power-98066.png

  • Physics-Work Energy and Power-98067.png
A ball of mass 10 kg is moving with a velocity of 10 m/s. It strikes another ball of mass 5 kg which is moving in the same direction with a velocity of 4 m/s. If the collision is elastic, their velocities after the collision will be, respectively
  • 6 m/s, 12 m/s
  • 12 m/s, 6 m/s
  • 12 m/s, 10 m/s
  • 12 m/s, 25 m/s
A body of mass 2 kg collides with a wall with speed 100 m/s and rebounds with same speed. If the time of contact was 1/50 second, the force exerted on the wall is
  • 8 N
  • 2)
    Physics-Work Energy and Power-98070.png
  • 4 N

  • Physics-Work Energy and Power-98071.png
A body falls on a surface of coefficient of restitution 0.6 from a height of 1 m. Then, the body rebounds to a height of
  • 0.6 m
  • 0.4 m
  • 1 m
  • 0.36 m
A hail is dropped from a height h. lithe coefficient of restitution he e, then to what height will it rise after jumping twice from the ground
  • eh/2
  • 2eh

  • Physics-Work Energy and Power-98074.png

  • Physics-Work Energy and Power-98075.png
A ball of weight 0.1 kg coming with speed 30 m/s strikes with a bat and returns in opposite direction with speed 40 m/s, then the impulse is (Taking final velocity as positive)

  • Physics-Work Energy and Power-98077.png
  • 2)
    Physics-Work Energy and Power-98078.png

  • Physics-Work Energy and Power-98079.png

  • Physics-Work Energy and Power-98080.png
A billiard ball moving with a speed of 5 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
  • 10 ms–1
  • 5 ms–1
  • 2.5 ms–1
  • 1.0 ms–1
A ball of mass m falls vertically to the ground from a height h1 and rebound to a height h2. The change in momentum of the ball on striking the ground is

  • Physics-Work Energy and Power-98082.png
  • 2)
    Physics-Work Energy and Power-98083.png

  • Physics-Work Energy and Power-98084.png

  • Physics-Work Energy and Power-98085.png
A body of mass 50 kg is projected vertically upwards with velocity of 100 m/sec. 5 sec after this body breaks into 20 kg and 30 kg. If 20 kg piece travels upwards with 150 m/sec, then the velocity of other block will be
  • 15 m/sec downwards
  • 15 m/sec upwards
  • 51 m/sec downwards
  • 51 m/sec upwards
A steel ball of radius 2 cm is at rest on a frictionless surface. Another ball of radius 4 cm moving at a velocity of 81 cm/sec collides elastically with first ball. After collision the smaller ball moves with speed of
  • 81 cm/sec
  • 63 cm/sec
  • 144 cm/sec
  • None of these
A ball is projected vertically down with an initial velocity from a height of 20 m onto a horizontal floor. During the impact it loses 50% of its energy and rebounds to the same height. The initial velocity of its projection is
  • 20 ms–1
  • 15 ms–1
  • 10 ms–1
  • 5 ms–1
A ball hits a vertical wall horizontally at 10 m/s bounces back at 10 m/s

  • Physics-Work Energy and Power-98090.png
  • There may be an acceleration because its initial direction is horizontal
  • There is an acceleration because there is a momentum change
  • Even though there is no change in momentum there is a change in direction. Hence it has an acceleration
A hail is allowed to fall from a height of 10 m. If there is 40% loss of energy due to impact, then after one impact ball will go up to
  • 10 m
  • 8 m
  • 4 m
  • 6 m
A body of mass m1 moving with a velocity 3 ms–1 collides with another body at rest of mass m2. After collision the velocities of the two bodies are 2 ms–1 and 5 ms–1 respectively along the direction of motion of m1. The ratio m1 / m2.

  • Physics-Work Energy and Power-98092.png
  • 5

  • Physics-Work Energy and Power-98093.png

  • Physics-Work Energy and Power-98094.png
0:0:1


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