JEE Questions for Physics Work Energy And Power Quiz 13 - MCQExams.com

A pump motor is used to deliver water at a certain rate from a given pipe. To obtain twice as much water from the same pipe in the same time, power of the motor has to be increased to
  • 16 times
  • 4 times
  • 8 times
  • 2 times
An engine pumps up 100 kg of water through a height of 10 m in 5s. given that the efficiency of the engine is 60%. If g = m/sec2, the power of the engine is
  • 3.3 kW
  • 0.33 kW
  • 0.033 kW
  • 33 kW
The power of pump, which can pump 200 kg water to a height of 50 m in 10 sec, will be
  • 10 × 103 watt
  • 20 × 103 watt
  • 4 × 103 watt
  • 60 × 103 watt
An engine pump is used to pump a liquid of density ρ 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

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An engine pumps water through a hose pipe. Water passes through the pipe and leaves it with a velocity of 2 m/s. The mass per unit length of water in the pipe is 100 kg/m. What is the power of the engine
  • 800 W
  • 400 W
  • 200 W
  • 100 W
A particle of mass M starting from rest undergoes uniform acceleration. If the speed acquired in time T is V, the power delivered to the particle is

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  • 2)
    Physics-Work Energy and Power-98438.png

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A body projected vertically from the earth reaches a height equal to earth\'s radius before returning to the earth. The power exerted by the gravitational force is greatest
  • At the instant just after the body is projected
  • At the highest position of the body
  • At the instant just before the body hits the earth
  • It remains constant all through
A mass m slips along the wall of a semispherical surface of radius R. The velocity at the bottom of the surface is
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  • 2)
    Physics-Work Energy and Power-98444.png

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A ball is projected vertically upwards with a certain initial speed. Another ball of the same mass is projected at an angle of 60° with the vertical with the same initial speed. At highest points of their journey, the ratio of their potential energies will be
  • 1 : 1
  • 2 : 1
  • 3 : 2
  • 4 : 1
The kinetic energy possessed by a body of mass m moving with a velocity v is equal to 1/2 mv2, provided
  • The body moves with velocities comparable to that of light
  • The body moves with velocities negligible compared to the speed of light
  • The body moves with velocities greater than that of light
  • None of the above statement is corrects
A bullet of mass 0.02 kg travelling horizontally with velocity 250 ms–1 strikes a block of wood of mass 0.23 kg which rests on a rough horizontal surface. After the impact, the block and bullet move together and come to rest after travelling a distance of 40 m. The coefficient of sliding friction of the rough surface is (g = 9.8 ms–2)
  • 0.75
  • 0.61
  • 0.51
  • 0.30
A rifle bullet loses 1/20th of its velocity in passing through a plank. The least number of such planks required just to stop the bullet is
  • 5
  • 10
  • 11
  • 20
A light and a heavy body have equal kinetic energy. Which one has a greater momentum
  • The light body
  • The heavy body
  • Both have equal momentum
  • It is not possible to say anything without additional information
A spherical ball of mass 20 kg is stationary at the top of a hill of height 100 m. It slides down a smooth surface to the ground, then climbs up another hill of height 30 m and finally slides down to a horizontal base at a height of 20 m above the ground. The velocity attained by the ball is
  • 10 m/s
  • 10√30 m/s
  • 40 m/s
  • 20 m/s
The force constant of a weightless spring is 16 N/m. A body of mass 1.0 kg suspended from it is pulled down through 5 cm and then released. The maximum kinetic energy of the system (spring + body) will be
  • 2 × 10–2 J
  • 4 × 10–2 J
  • 8 × 10–2 J
  • 16 × 10–2 J
If the kinetic energy of a body becomes four times of its initial value, then new momentum will
  • Becomes twice its initial value
  • Becomes three times its initial value
  • Become four times its initial value
  • Remains constant
A bomb is 12 kg divides in two parts whose ratio of masses is 1 : 3. If kinetic energy of smaller part is 216 J, then momentum of bigger part in kg-m/sec will be
  • 36
  • 72
  • 108
  • Data is incomplete
If a body of mass 200 g falls from a height 200 m and its total P.E. is converted into K.E. at the point of contact of the body with earth surface, then what is the decrease in P.E. of the body at the contact (g = 10 m/ s2)
  • 200 J
  • 400 J
  • 600 J
  • 900 J

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    Physics-Work Energy and Power-98459.png

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An ice cream has a marked value of 700 kcal. How many kilowatt-hour of energy will it deliver to the body as it is digested
  • 0.81 kWh
  • 0.90 kWh
  • 1.11 kWh
  • 0.71 kWh
A stationary particle explodes into two particles of a masses m1 and m2 which move in opposite directions with velocities v1 and v2. The ratio of their kinetic energies E1 / E2 is
  • m1 / m2
  • 1
  • m1 v2/m2 v1
  • m2/m1
A bomb of mass 3.0 kg explodes in air into two pieces of masses 2.0 kg and 1.0 kg. The smaller mass goes at a speed of 80 m/s. The total energy imparted to the two fragments is
  • 1.07 kJ
  • 2.14 kJ
  • 2.4 kJ
  • 4.8 kJ
The spheres A and B masses m1 and m2 respectively collide. A is at rest initially and B is moving with velocity v along x-axis, After collision B has a velocity v/2 in a direction perpendicular to the original direction.The mass A moves after collision in the direction
  • Same as that of B
  • Opposite to that of B
  • θ = tan–1 (1 /to the x-axis
  • θ = tan–1 (–1 /to the x-axis
A shell initially at rest explodes into two pieces of equal mass, then the two pieces will
  • Be at rest
  • Move with different velocities in different directions
  • Move with the same velocity in opposite directions
  • Move with the same velocity in same direction
A lead ball 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
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 gun fires a bullet of mass 50 g with a velocity of 30 m sec–1. Because of this the gun is pushed back with a velocity of 1 m sec–1. The mass of the gun is
  • 15 kg
  • 30 kg
  • 1.5 kg
  • 20 kg
A smooth sphere of mass M moving with velocity u directly collides elastically with another sphere of mass m at rest. After collision their final velocities are V and v respectively . The value of v is

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    Physics-Work Energy and Power-98470.png

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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
  • m >> M
  • m << M
  • m = M

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A particle of mass m moving with horizontal speed 6 m/sec as shown in figure. If m << M then for one dimensional elastic collision, the speed of lighter particle after collision will be
Physics-Work Energy and Power-98475.png
  • 2 m/sec in original direction
  • 2 m/sec opposite to the original direction
  • 4 m/sec opposite to the original direction
  • 4 m/sec in original direction
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

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Two equal masses m1 and m2 moving along the same straight line with velocities +3 m/s and –5 m/s respectively collide elastically. Their velocities after the collision will be respectively
  • +4 m/s for both
  • –3 m/s and +5 m/s
  • –4 m/s and +4 m/s
  • –5 m/s and +3 m/s
At high altitude, a body explodes at rest into two equal fragments with one fragment receiving horizontal velocity of 10 m/s. Time taken by the two radius vectors connecting point of explosion to fragments to make 90° is
  • 10s
  • 4s
  • 2s
  • 1s
If two balls each of mass 0.06 kg moving in opposite directions with speed 4 m/s collide and rebound with the same speed, then the impulse imparted to each ball due to other is
  • 0.48 kg-m/s
  • 0.24 kg-m/s
  • 0.81 kg-m/s
  • Zero
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 the above
A ball is projected vertically down with an initial velocity from a height of 20 m into 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 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
Two masses mA and mB moving with velocities vA and vB in opposite directions collide elastically. After that the masses mA and mB move with velocity vB and vA respectively. The ratio (mA / mB) is
  • 1
  • 2)
    Physics-Work Energy and Power-98487.png

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Two bodies having same mass 40 kg are moving in opposite direction, one with a velocity of 10 m/s and the other with 7 m/s. If they collide and move as one body, the velocity of the combination is
  • 10 m/s
  • 7 m/s
  • 3 m/s
  • 1.5 m/s
A ball of mass m moving with velocity V, makes a head on elastic collision with a ball of the same mass moving with velocity 2V towards it. Taking direction of V as positive velocities of the two balls after collision are
  • –V and 2V
  • 2V and –V
  • V and –2V
  • –2V and V
A mass of 100 g strikes the wall with speed 5 m/s at an angle as shown in figure and it rebounds with the same speed. If the contact time is 2 × 10–3 sec, what is the force applied on the mass by the wall

  • Physics-Work Energy and Power-98492.png
  • 250 N to right

  • Physics-Work Energy and Power-98493.png
  • 250 N to left

Physics-Work Energy and Power-98495.png
  • 2
  • 4
  • 6
  • 8
A body of mass m is at rest. Another body of same mass moving with velocity V makes head on elastic collision with the first body. After collision the first body starts to move with velocity
  • V
  • 2V
  • Remains at rest
  • No predictable
A ball moving with velocity 2 m/s collides head on with another stationary ball of double the mass. If the coefficient of restitution is 0.5, then their velocities (in m/s.) after collision will be
  • 0, 2
  • 0, 1
  • 1, 1
  • 1, 0.5
The potential energy of a conservative system is given by V(x) = (x2 – 3x) joule. Then its equilibrium position is at
  • x = 1.5 m
  • x = 2 m
  • x = 2.5 m
  • x = 3 m
  • x = 0.33 m
A force F = – K (yi + xj) (where K is a positive constant) acts on a particle moving in the xy-plane. Starting from the origin, the particle is taken along the positive x-axis to the point (a,and then parallel to the y-axis to the point (a, a). The total work done by the force F on the particles is
  • –2Ka2
  • 2Ka2
  • –Ka2
  • Ka2
An open knife edge of mass \'m\' is dropped from a height `h\' on a wooden floor. If the blade penetrates upto the depth \'d\' into the wood, the average resistance offered by the wood to the knife edge is
  • mg
  • 2)
    Physics-Work Energy and Power-98500.png

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A shell is fired from a cannon with velocity v m/sec at an angle θ with the horizontal direction. At the highest point in its path it explodes into two pieces of equal mass. One of the pieces retraces its path to the cannon and the speed in m/sec of the other piece immediately after the explosion is
  • 3v cosθ
  • 2v cosθ

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A mass of M kg is suspended by weightless string, horizontal force that is required to displace it until the string makes an angle of 45° with the initial vertical direction is

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  • 2)
    Physics-Work Energy and Power-98508.png

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A particle of mass m moving eastward with a speed v collides with another particle of the same mass moving northward with the same speed v. The two particles coalesce on collision. The new particle of mass 2m will move in the north-easterly direction with a velocity
  • v/2
  • 2v
  • v/√2
  • v
0:0:1


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