Free NEET Physics multiple-choice questions on Power. Attempt each question and reveal the answer with a full explanation.
A particle moves with a velocity v = (5 i - 3 j + 6 k ) m/s under the influence of a constant force F = (10 i + 10 j + 20 k ) N. The instantaneous power applied to the particle is: 140 W 45 W 100 W 170 W A particle moves with a velocity v = (5 i + 2 j - 3 k ) m/s under the influence of a constant force F = (10 i + 10 j + 20 k ) N . The instantaneous power applied to the particle is: 10 W 70 W 100 W 50 W Which of the following is not a unit of power? kWh Watt J/s Horsepower A water pump rates 2 kW . If g = 10 m/s 2 , the amount of water it can raise in one minute to a height of 10 m is: 1200 liters 100 liters 2000 liters 600 liters A water pump lifts 100 kg of water to a height of 10 m in 5 seconds . The power of the pump is: (Take g = 10 m/s 2 ) 2000 W 1000 W 500 W 4000 W A body of mass m is moving with a constant acceleration a . The power delivered by the force at time t is: ma 2t mat ma 2t 2 1 2 ma 2t A machine gun fires n bullets per second, each of mass m and velocity v . The power of the gun is: 1 2 nmv 2 nmv 2 2nmv 2 1 4 nmv 2 An engine of power P delivers a force F on a car which is moving with velocity v . If the velocity of the car is doubled, the force delivered by the engine (keeping power constant) is: F/2 2F F/4 4F A body of mass m is moving with a constant acceleration a . The power delivered by the force at time t if it starts from rest is: ma 2t mat ma 2t 2 1 2 ma 2t The power of a pump which can pump 200 kg of water to a height of 50 m in 10 seconds is: ( g = 10 m/s 2 ) 10 kW 5 kW 20 kW 100 kW Which of the following is the dimension of Power? [ML 2T -3 ] [ML 2T -2 ] [MLT -2 ] [ML 2T -1 ] A body of mass m is dropped from a height h . The power delivered by gravity as a function of time t is: mg 2t 1 2 mg 2t mgt mg 2t 2 Two bodies A and B of same mass undergo completely inelastic one dimensional collision. The body A moves with velocity v 1 while body B is at rest before collision. The velocity of the system after collision is v 2 . The ratio v 1 : v 2 is 1 : 2 2 : 1 4 : 1 1 : 4 A ball of mass 0.5 kg is dropped from a height of 40 m. The ball hits the ground and rises to a height of 10 m. The impulse imparted to the ball during its collision with the ground is (Take g = 9.8 m/s 2 ) 84 NS 21 NS 7 NS 0 A particle of mass m is driven by a machine that delivers a constant power k watts. If the particle starts from rest, the displacement of the particle at time t is: ( 8k 9m ) 1/2 t 3/2 ( k m ) 1/2 t 3/2 ( 4k 3m ) 1/2 t 3/2 ( k 2m ) 1/2 t 2 A body of mass 1 kg begins to move under the action of a time-dependent force F = (2t i + 3t 2 j ) N, where t is time in seconds. The power developed by the force at time t is: (2t 3 + 3t 5) W (2t 2 + 3t 3) W (5t 3) W (2t 2 + 4t 4) W A body of mass m is accelerated uniformly from rest to a speed v in time T . The instantaneous power delivered to the body as a function of time t is: mv 2t T 2 mv 2t 2 T mv 2t T mv 2t 2 T 2 An elevator can carry a maximum load of 1800 kg (elevator + passengers) is moving up with a constant speed of 2 m/s. The frictional force opposing the motion is 4000 N. The minimum power delivered by the motor to the elevator in watts is: ( g = 10 m/s 2 ) 44000 W 22000 W 36000 W 4000 W A force F is applied to a body which is initially at rest. The power delivered to the body varies with time as P = kt 2 . The change in kinetic energy of the body between t=2 s and t=4 s is: 56k 3 64k 3 24k 12k A machine gun fires 60 bullets per minute with a velocity of 700 m/s. If each bullet has a mass of 50 g, find the power developed by the gun. 12250 W 24500 W 6125 W 1225 W The power of a water pump is 2 kW. If g = 10 m/s 2 , the amount of water it can raise in one minute to a height of 10 m is: 1200 liters 120 liters 2000 liters 200 liters A constant power P is applied to a car of mass m . The velocity of the car at any time t starting from rest is: 2Pt/m Pt/m Pt/m 2Pt/m An engine of a car delivers a constant power P . The acceleration of the car of mass m at a velocity v is: P/mv P/m Pv/m P/v 2 Water is falling on the blades of a turbine at a rate of 6 10 3 kg/min. The height of the fall is 10 m. The power given to the turbine is ( g = 10 m/s 2 ): 10 kW 1 kW 60 kW 100 kW The wind is blowing with a velocity v perpendicular to the area A of a windmill. If the density of air is , the maximum electrical power produced is proportional to: v 3 v 2 v v 4 The power of a motor is 2 HP. The time taken by the motor to lift 600 kg of water from a well 20 m deep is ( 1 HP = 746 W, g = 10 m/s 2 ): 80.4 s 40.2 s 120.6 s 60 s A particle moves with a velocity v = (kv) i such that its power remains constant. The acceleration of the particle is proportional to: v -1 v v 2 v 0 A body of mass 5 kg is moving with a velocity of 10 m/s . A force is applied to it so that in 20 seconds , it attains a velocity of 25 m/s . The power of the force is: 65.6 W 75 W 100 W 50 W The power required to keep a car moving at a constant speed v against an air resistance force which is proportional to the square of the speed ( F d = kv 2 ) is P . If the speed of the car is increased by 25 % , the power required will increase by approximately: 95 % 25 % 56 % 125 % A particle of mass m is moving in a circle of radius r with a constant tangential acceleration a t . The power delivered to the particle by the resultant force at time t is: ma t 2t ma t 2t 2 1 2 ma t 2t m a t r A particle moves with a velocity v = at i + b j where a and b are constants. The power delivered by the resultant force at time t is: ma 2t mab ma 2 m(at+b) 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 : 524 J 256 J 486 J 324 J A 0.5 kg ball moving with a speed of 12 m/s strikes a hard wall at an angle of 30 with the wall. It is reflected with the same speed and at the same angle. If the ball is in contact with the wall for 0.25 seconds, the average force acting on the wall is:- 48 N 24 N 12 N 96 N A particle of mass m is moving in a circular path of radius R . If its speed v is increasing at a constant rate a , the power delivered to the particle is: mav mv 2/R Zero ma 2/R An explosion blows a rock into three parts Two parts go off at right angles to each other. These two are, 1 kg first part moving with a velocity of 12 ms -1 and 2 kg second part moving with a velocity of 8 ms -1 . If the thirds part files off with a velocity of 4 ms -1 , its mass would be : 3 kg 5 kg 7 kg 17 kg An explosion breaks a rock into three parts in a horizontal plane. Two of them go off at right angles to each other. The first part of mass 1 kg moves with a speed of 12 ms -1 and the second part of mass 2 kg moves with 8 ms -1 speed. If the third part flies off with 4 ms -1 speed, then its mass is 3 kg 5 kg 7 kg 17 kg A body of mass (4m) is lying in x-y plane at rest. It suddenly explodes into three pieces. Two pieces, each of mass (m) move perpendicular to each other with equal speeds (v). The total kinetic energy generated due to explosion is :- mv 2 3 2 mv 2 2mv 2 4mv 2 A body initially at rest, breaks up into two pieces of masses 2 M and 3 M respectively, together having a total kinetic energy E. The piece of mass 2 M, after breaking up, has a kinetic energy : 2E 5 E 2 E 5 3E 5 A moving block having mass m, collides with another stationary block having mass 4m. The lighter block comes to rest after collision. When the initial velocity of the lighter block is v, then the value of coefficient of restitution (e) will be 0.8 0.25 0.5 0.4 Body A of mass 4m moving with speed u collides with another body B of mass 2m , at rest. The collision is head on and elastic in nature. After the collision the fraction of energy lost by the colliding body A is : 5 9 1 9 8 9 4 9 A shell of mass m is at rest initially. It explodes into three fragments having mass in the ratio 2 : 2 : 1. If the fragments having equal mass fly off along mutually perpendicular directions with speed v , the speed of the third (lighter) fragment is 2 v 2 2 v 3 2 v v 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 The heart of a man pumps 5 liters of blood through the arteries per minute at a pressure of 150 mm of mercury. If the density of mercury be 13.6 10 3 kg/m 3 and g = 10 m/s 2 , then the power of heart in Watt is: 1.70 2.35 3.0 1.50 A particle of mass m is driven by a machine that delivers a constant power k watts. If the particle starts from rest, the force on the particle at time t is: mk 2t 1 2 mkt mk t -1/2 2mk t -1/2 The power of a water pump is 2 kW. If g = 10 m/s 2 , the amount of water it can raise in one minute to a height of 10 m is: 1200 kg 120 kg 2000 kg 600 kg A particle of mass m moves in a circular path of radius r such that its centripetal acceleration a c is given by a c = k 2rt 2 , where k is a constant. The power delivered to the particle by the forces acting on it is: mk 2r 2t mk 2rt 2 mk 2rt 0 A body of mass 2 kg is driven by a machine that delivers a constant power of 2 W . If the body starts from rest, the distance moved by the body in t seconds is: 2 3 t 3/2 2 t 3/2 1 3 t 3/2 t 3/2 A block of mass m is pulled along a horizontal surface with a constant velocity v by a force F at an angle with the horizontal. If the coefficient of friction is , the power delivered by the force is: mg v + mg v Fv mg v - A particle of mass m is moving in a circular path of constant radius r such that its centripetal acceleration a c is varying with time t as a c = k 2 r t 2 , where k is a constant. The power delivered to the particle by the forces acting on it is: mk 2 r 2 t mk 2 r t 2 mk 2 r 2 t 2 0 The heart of a man pumps 4 liters of blood per minute at a pressure of 130 mm of Hg. If density of Hg is 13.6 10 3 kg/m 3 , the power of the heart is: 1.15 W 11.5 W 0.115 W 115 W A pump is used to lift 500 kg of water from a depth of 80 m in 10 seconds . The efficiency of the pump is 70 % . The power of the intake motor is ( g = 10 m/s 2 ): 57.1 kW 40 kW 28 kW 80 kW Sand is falling on a conveyor belt at a constant rate of M kg/s. To keep the belt moving with a constant velocity v m/s, the additional power required is: Mv 2 1 2 Mv 2 2Mv 2 1 4 Mv 2 A machine delivers a constant power P . The velocity of a particle of mass m starting from rest as a function of distance s is proportional to: s 1/3 s 1/2 s 2/3 s The area under the 'reciprocal of power' vs 'velocity' graph (i.e., 1/P vs v ) represents: Mass divided by force times distance Displacement per unit mass Time taken per unit mass Momentum change A engine of a car delivers constant power P . If the car of mass m starts from rest, the distance traveled by the car in time t is given by: 8P 9m t 3/2 P m t 2 1 2 P m t 2 2P m t 1/2 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 the energy. How much power is generated by the turbine? ( g = 10 m/s 2 ) 8.1 kW 12.3 kW 7.0 kW 10.2 kW If a force F = (2 i + 3 j + 4 k ) N acts on a body for 4 s and produces a displacement d = (3 i + 4 j + 5 k ) m, the power used is: 9.5 W 7.5 W 38 W 19 W A body of mass m is moving with constant acceleration a . The power delivered by the force at any time t is (starting from rest): ma 2t mat ma 2t 2 1 2 ma 2t A crane lifts a mass of 100 kg to a height of 10 m in 20 s. The power of the crane is: ( g = 10 m/s 2 ) 500 W 1000 W 2000 W 250 W