Work, power & energy Questions and Answers

ALLEN CAREER ISTITUTE MARJANTARE TARGET PRE MEDICAL 2022 A body of mass 10 kg is moving along a smooth inclined plane 0 60 with constant velocity through a distance of 10 m Then work done on the body by gravitational force is 1 500 J 2 500 3J 3 1000 31 4 1000 J

2022 NEET NURTURE PHASE I TO I INTERNAL TEST 06 23 09 2020 HAVE CONFIDENCE 100 SUCCESS YSICS A particle moves from 3 23 6k m to 141 13 9k m Under the action of force 41 3 3k N the work done on the particle is 2 100 J 1 10 J 2 1000

act on a body in x direction find the work X done in displacing the body from x a to x 2a k is a positive constant If F 1 3 2a 4a k 2a 4a

K 48 The potential energy of a 1 kg particle free to move along x axis is given by U x 4 2 total mechanical energy of the particle is 2J Then the maximum speed in m s is 1 2 3 3 2 2 2 4 2 J The

A man drags a box with uniform speed across a 10 m rough floor The coefficient of friction of the floor is 0 5 If the man pulls the box with a force of 3 kN at an angle 30 with the horizontal what is the work done in dragging the box A 30 kJ 15 C kJ B 15 kJ D 5 Kj

Power supplied to a particle of mass 2 kg varies with time as P 3t watt Here t is time in 2 second If velocity of particle at t 0 is v 0 the velocity of particle at time t 2 s will be A 1 m s C 2 m s B 4 m s D 2 2 m s

A 10 kg block is pulled along a frictionless surface in the form of an arc of a circle of radius 10 m The applied force F is 200 N as shown in figure If the block started from rest at P then A the velocity at Q would be 20 m s B the velocity at Q would be 27 m s C work done by gravity is negative D work done by gravity is positive

A block of mass 2 kg is pulled along circular arc from position X to Y as shown in figure The work done by the horizontal force is pulling the block from X to Y is R 30 X 1 FR sin 30 3 FR tan 30 R F F 2 FR cos 30 4 FR cot 30

The bob of a pendulum is released from a horizontal position If the length of the pendulum is 1 5 m what is the speed with which the bob arrives at the lowermost point given that it dissipated 5 of its initial energy against air resistance

A 30 kg box is pulled across a level floor by a rope that is angled 20 degrees above the horizontal and to the right The coefficient of kinetic friction is 0 1 The tension in the rope is 75 N a Find all the forces acting on the box b Find the work done by each force if the box moves 8 m to the right Show your work

An object of mass m is thrown with a velocity vo toward spring as shown in figure in natural length Find value of vo such that it will compress the spring by a distance L Ans Vo k 2 m 4a 2 g 2 X 0 m

8 On a frictionless surface of variable slope a block of mass 2 kg at rest is pushed by applying a horizontal constant force of 40 N as shown The block reaches the top and leaves the surface and falls under gravity alone It strikes the surface some distance away with a speed of 1 10 m s 3 40 m s 40 m 2 20 m s 4 60 m s

A block of mass slides on a rough inclined plane with constant velocity V and reaches the horizontal surface The work done by all the forces on the block is A mgh mg cos 0 h C zero mg sin 0 cos 8 h B D 0

A conveyor belt is used to move luggage in an airport from the ground into the hold of a plane The belt lifts a pile of suitcases with a combined mass of 120 kg 15 m up a 14 slope The luggage starts from rest at the bottom of the slope and accelerates uniformly until it reaches the top with a velocity of 2 2 m s a Calculate i The total work done by the conveyor belt in moving the luggage Ignore any friction in the movement of the conveyor belt

A massless spring of spring constant k has two ends P and Q as shown in the figure End Q is being pulled by person B with constant speed u towards right End P is being pushed by person A with constant acceleration a towards starting from rest Both starts simultaneously Choose the correct option at the instant when B appears to be at rest with respect to A right A P a A B C mmmm O u B work done by B ku 3a work done by A 5ku 24a work done by A 5ku 24a

PHYSI Gradually lowered mass stretches the spring by y metre If same body attached to the same spring is released suddenly the maximum stretch in this will be A same B double C triple D half T

36 4 Smaller normal reaction A force of 5 3x N acting on a body of 20 kg along the x axis displaces it from x to x 6 m The work done by the force 1 20 J 2 48 J 3 68 J

5 In an electron microscope if the potential is increased from 20 KV to 80 KV the resolving power of the microscope will change from R to 1 R 3 2R 2 4R 4 2

A particle of charge q and mass m is moving along the x axis with a velocity v and enters a region of electric field E and magnetic field B as shown in figure below For which figure the net force on the charge may be zero 1 3 gv 9 V MAJOR SRG AC E B E B 2 4 gov 9V B AY E E B X

hui hai bucket nhi laga hai Bucket ke khud ke hee weight ke kaaran rope toot gyi aur niche gir gyi Aur girne ki awaaz bhi aai Yeh elastic collision hai ya inolastic allicion pe koi external force

A particle of mass m moving along the quarter section of the circular path whose centre is at the origin The radius of the circular path is a m A force F v x N acts on the particle where x y denotes the co ordinates of position of the particle Calculate the work done by the force in taking the particle from point A a 0 to point B 0 a along the circular path B 0 a

Q 19 Equipotential lines arising from a static charge distribution has been shown in a certain region of space a Draw the electric field lines starting from point A b If a charge is released at A will it move along the field line passing through A c How much work is done by the electric force if a charge moves from B to C Is the knowledge of path important in this calculation 50 V 40 V 30 V 20 V 10 V 0 60 V 70 V B C A 80 V 90 V

A block of mass m is attached to a spring of force constant k Charge on the block is q A horizontal electric field E is acting in the direction as shown Block is released with the spring in unstretched position Mark incorrect statement k eeeee eeeee Smooth q m O Block will execute SHM Amplitude of oscillation is E O Time period of oscillation is 21 Block will oscillate but harmonicall m tmpt simple

point by a A heavy particle hanging from a fixe light inextensible string of length is projected horizontally with speed gl Then the speed of the particle and the inclination of the string to the vertical at the instant of the motion when the tension in the string equal the weight of the particle A 31 0 C 3g cos 3 2 B cos 2 3 D lg V 3 cos 2 3 sin 2 3

6 The chain is released see figure What is the speed when it slips by length 4 L 2 re mag 1 3 If the z 3 gL 16 3gL 8 8 4 a Exem 2 4 M L 2 5gL 8 5gL V 16 6 he Tirts F 6 Pol

A particle is moving under the potential V x cx dx Here c and d are constant The particle is at rest initially and is at stable point Calculate the minimum speed of the particle when it reached to unstable point a Vmin b Vmin c v min d v min d 27mc 8d 27mc 2d 9mc 16d 27mc

Two pendulum bobs A and B of mass m and 2m respectively are simultaneously released from a height H above the lowest point making an elastic collision at the lowest point If after the first collision A and B rise to heights h and he respectively then h 2h is 1 3H 2 H 3 H 3 4 2H

3 C 84 If the maximum height of a particle after third collision from ground is 60 m calculate the initial height from which it was dropped if the coefficien of restitution is e 1 3 60 60 2 60 4 60

The above graph shows PE of a particle At x 1 m the KE of particle is 1 J The particle reverses its of motion at x SolveLancer Test 5 U e 1 0 I a 1 m b 5 m c 6 m d 2 m I 1 I I I 1 X 1 X 1 11 I I I 5 I I I I x m

In a Young s double slit experiment if there is n initial phase difference between the light from th two slits a point on the screen corresponding the fifth minimum has path difference NEET 2019 Odisha 2 5 1 2 1 11 1 2 3 102 4 94

If under the action of applied forces a block is displaced by 10 m towards right as shown in figure Then the work done by 50 N force is 1 1000 J 50 N 2 1000 J 3 500 J 100 N 4 500 J

Aforce F x 3 00x iz acts on a particle as the particle moves along anxaxis within newtons x in meters and ca constant Atx 0 m the particle s kinetic energy is 20 0 J at x 3 00 m it is 11 0 J Find c Number Units

39 An ideal heat engine operates in a Carnot cycle between 227 C and 127 C It absorbs 6 kJ of heat at the higher temperature The amount of heat converted into work is a 1 2 kJ c 3 5 kJ b 1 6 kJ d 4 8 kJ CBSE PMT 3

A block of mass 2 kg is tied to elastic thread of unscratched length 2 m and suspended to point O initially block is horizontal level to this point O Now block is released and its speed is 5 m s when thread is vertical If the acceleration of the block at the lowest position is K Find the value of K 4m 2m angz W

The elevator E has a mass of 3000 kg when fully loaded and is connected as shown to a counterweight W of mass 1000 kg Determine the power in kilowatts delivered by the motor a when the elevator is moving down at a constant speed of 3 m s b when it has an upward velocity of 3 m s and a deceleration of 0 5 m s

A 50 kg man with 20 kg load on his head climbs up 20 steps of 0 25 m height each Then the work done against gravity in climbing is take g 10 m s 2 350 J 1 5 J 3 100 J 4 3500 J If any how speed of light in vacuum becomes 1 5 times its initial speed then new value of light year

When the displacement is half of the amplitude then ratio of potential energy to the tota energy is 1 1 2 3 feff 2 1 4 3 1 4 1 8

Q 8 A block of mass m is taken from A to B slowly under the action of a constant force F Work done by this force is 1 FR 3 FR O 13 90 R 1 B 1 B m F circular arc 2 F 2 FR 4 FR

4 A simple pendulum consists of string of length L and suspended mass m It is released from horizontal position as shown in the figure Speed of the mass when the string becomes vertical will be s L am fafted 2044 m a af frafa ya CRI CENTER OF www L m A aL

cable exerts a constant upward tension of magnitude 1 58 x 10 N on a 1 40 x 10 kg elevator as it rises through a vertical distance of 1 70 m HINT a Find the work done by the tension force on the elevator in J 1 b Find the work done by the force of gravity on the elevator in J 1

A student produces a power of P 0 71 kW while pushing a block of mass m 63 kg on an inclined surface making an angle of 0 6 5 degrees with respect to the horizontal The coefficient of kinetic friction between the block and the incline is uk 0 11 Write an expression for the maximum constant speed vm the block travels at under the power applied by the student What is the speed vm in m s

Q 5 The system shown in figure is released from rest with spring at natural length The spring starts extending as soon as it is released Neglect friction and masses of pulley string and spring www M m

29 A shell of mass 200g is ejected from a gun of mass 4kg by an explosion that generates 1 05 kJ of energy The initial velocity of the shell is 2 80 ms 1 1 100 ms 1 3 40 ms 1 4 120 ms 1

questions also refers to the same famous Cyclone roller coaster ride at Coney Island shown in the sketchbelow Assume no friction A A 50 m 25 r P R How fast must the coaster be moving at P in order to coast to a stop at Q 22 m s

Physics Part A ii Maximum Marks 21 This section has 7 questions Each question has FOUR options A B C and D Only ONE of these four option s is correct Marking scheme o 3 If the correct option is selected 1 In case if selected typed option is incorrect 0 In case if no response is typed selected A block of mass m is pulled by a constant power P placed on a rough horizontal plane The friction co efficient between the block and surfa with its speed vas Vito The acceleration of the block when its speed is 3 m s will be OP 3m O O 3m 9 2 9 2 92

In the figure shown C is a fixed wedge on horizontal surface Blocks A and B are of masses m and 2m respectively are kept as shown in figure They can slide along the incline plane smoothly The pulley and string are massless The inclined planes are very long A and B are released from rest 2 seconds after the release B is caught for a moment and released again Then Take 30 and g 10m s Choose the correct option s 0 30 C B A the speed of A just before the instant when the string becomes tight again will be 10 3 m s B the speed of A just before the instant when the string becomes tight again will be zero C the speed of A just after the instant when the string becomes tight again will be 20 9 m s D the speed of A just after the instant when the string becomes tight again will be 10 3 m s

27 A particle accelerating uniformly has velocity v at time t Calculate the work done on the particle in time t t t 1 mv 2 1 2 t 2 3 mv 12 12 1 2 4 2 1 m 2 2mv 2 1 1 1

A small particle of mass m is released from rest in the position shown and swings freely in vertical plane first about and then about a peg A Vertically below the point O after cord comes in contact with the peg A Find the value of OA if particle just complete the circle about A length of string is and string is massless and inextensible O O 0 6 0 4

One end of a 10 cm long silk thread is fixed to a large vertical surface of a charged nonconducting plate and the other end is fastened to a small ball having a mass of 10 g and a charge of 4 0 x 10 C In equilibrium the thread makes an angle of 60 with the vertical Find the surface charge density on the plate 6 klam n Find

1 Two charges q and q2 are placed 30 cm apart as shown in the figure A third charge q3 is moved along the arc of a circle of radius 40 cm from C to D The change in the potential energy of the system is 93 k where k is 4 EO 1 892 9 93 CP 40 cm 9 92 A 30 cm B D AIPMT Prelims 2005 2 89 LAY