Work, power & energy Questions and Answers

A spring of unstretched length I has a mass m with one end fixed to a rigid support Assuming spring to be made of a uniform wire the kinetic energy possessed by it if its free end is pulled with uniform velocity v is Online April 12 2014 12 12 a 1 my b

3 A block of mass m is released from rest Initially the spring is unstretched The pulley and strings are ideal The maximum energy stored in the spring is 1 m g 4k 2 427 42 4 ng 000000 O m 2 2 2m g k

The system shown in the figure is released from rest After the 60 kg block strikes the ground it does not rebound Find the total distance in meter moved by the 30 kg block on the incline before coming to rest for the first time 30 kg 370 0 5 60 kg 6m

A coil of 40 henry inductance is connected in series with a resistance of 8 ohm and the combination is joined to the terminals of a 2 volt battery The time constant of the circuit is a 5 seconds c 40 seconds b 1 5 seconds d 20 seconds

0 A block of mass m is moved slowly from position 1 to position 2 by applying a tangential forc F of variable magnitude The spring has negligible mass and force constant k End of the spring moves in an arc of radius R When block is at position 1 the spring is at natural length Mark the CORRECT statement s R 1 A Work done by force F mgRsine B Work done by gravity mgRsine C Work done by spring force k RO eeeeeeee k RO 1 Unstrectched length

System shown in the figure is released from rest Pulley and spring are massless and the friction is absent everywhere The speed of 5kg block when 2kg block leaves the contact with ground is Take force constant of the spring K 40N mand g 10m s A 2m s B 2 2m s C 2m s reeee 5kg On 2kg

which a body of radius R so that 2016 1 circle of radius 20 The heart of a man pumps 5 litres of blood through t arteries per minute at a pressure of 150 mm of mercur If the density of mercury be 13 6 x 10 kg m an g 10m s then the power of heart in watt is a 1 50 b 1 70 c 2 35 2015 R d 3 0

A uniform rope suspended between two level nails A and B assume a curved shape ABC as shown in the figure The midpoint C of the rope is pulled vertically down to a position D to make a V shape and released When the rope again acquires the curved shape ACB the midpoint is pulled vertically upto a position E to make an inverted V shape If in these two pulling processes total work done by the pulling agency is 10J how much work will be done by the pulling agency in lifting vertically the midpoint from equilibrium to a position F in level with the nails 2 in 1

The potential energy U in Joule of a particle of mass 1kg moving in x y plane obeys the law U 3x 4y where x y are the co ordinate of the particle in metre If the particle is at rest at 6 4 at t 0 then A The particle has constant acceleration B The work done by the force from the position of rest of the particle to the instant of crossing the x axis is 25 J C The speed of the particle when it crosses the y axis is 10 m s D The co ordinates of the particle at time t 4s are 18 28

5 Find the speed in m s of mass m when it reaches O Initially the mass was at rest and all contacts are frictionless Initially D 4m x 3m and natural length of the spring is 3m K 6 N m and m 2kg D 00000 roo m X m

A force F y x z i 3xy 5z j 4zk is applied on a particle The work done by the force when the particle moves from the point 0 0 0 to the point 2 4 0 on the path shown W 10 in figure is W units is equal to 2 4 y 2x

city 0 on re be 4 89 A ball moving transitionally collides elastically with another stationary ball of the same mass At the moment of impact the angle between the straight line passing through the centres of the balls and the direction of the initial motion of the striking ball is equal to 45 Assuming the balls to be smooth find the fraction of the kinetic energy of the striking ball that turned into potential energy at the moment of the maximum deformation Ang 50 251

SolveLancer Test A person wants to raise 0 45 m of water through a height of 50 m with the help of a water pump Find the input power drawn by the pump in 5 minutes Efficiency of water pump 0 6 SolveLancer Test a 750 W b 1250 W c 450 W d 600 W

Two balls are dropped from the top of a cliff at a time interval At 2 s The first ball hits the ground rebounds elastically reversing direction nstantly without losing speed and collides with the second ball at height h 55 m above the ground How high is the top of the cliff

ball released from a certain height falls in the influence of gravity rikes the ground and repeatedly rebounds elastically During a time terval t 8 s from the instant it is released it covers a distance s 20 1 How many collisions during this time did the ball make with the round Acceleration of free fall is g 10 m s

on a body moving along X axis 48 The force acting varies with the position of the particle as shown in the figure The body is in stable equilibrium at a x x F and ro x1 b x x d Noith

32 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 0 and then parallel to the y axis to the point a a The total work done by the forces F on the particle is a 2ka 2 2 b 2ka 4 c ka 2 d ka

An electron m 9 x kg e of energy 10 v is circulating at right angle to a uniform magnetic field The speed of the electron is 10 e m 9 1031 kg e 1 6 10 19C g ta i B1 342 T Options 1 2 3 8 x 106 m s 1 9 x 10 2 m s

32 The gravitational field in a region is g given by F 10 N i 1 kg What will be work done by an external agent to slowly shift a particle of mass 2 kg from the point 0 0 to a point 5 4 a 180 J b 100 J C 180 J d 100 J 33 The liquids shown in figuro

discharge through a resistor by closing the key at the instant t 0 At the instant t In4 s the reading of the ammeter falls half the initial value The resistance of the ammeter is equal to C 0 5 F A B E A 1 MQ 102 C 202 202 www

Av A quantity X is given by A Ay where n is coefficient of viscosity of a fluid A is area Av is change and Ay is change in height The dimensional of formula for X is the same as that of 1 Work 2 Pressure

View in English A particle collides elastically with two moving walls one by one as shown on a horizontal plane Find the final speed of the particle after two collisica 3m s 5m s 1 4 11 m s 19 m s 21 m s 5 m s 3m s M

2 In the figure a simple pendulum is released from rest in the horizontal position OA and falls in a vertical plane under the influence of gravity If it strikes a vertical wall at B and the coefficient of restitution is 0 89 find the angle o defining its total rebound b What will be the velocity of rebound of the ball just after the third rebound 12 WY

A homogenous chain of linear density 0 02 kg m hangs from two poles located at x a The equation of the curve formed by the chain is ex b e x b y b 2 Find its potential energy in Joules with respect to the ground i e y 0 Here b 2 meters and a b In 2 You can also use the approximation In 2 11 16 and take g 10 m s

27 The angular amplitude of a simple pendulum is 00 The maximum tension in its string will be a mg 1 0 c mg 1 02 now witam b mg 1 0 d mg 1 03 2016

In law of conservation of energy during free fall is mechanical energy constant at every single point during free fall I know that if w e take position A B C there the mechanical e nergy is constant but I am saying that is me chanical energy constant at every single poi nt

160 If a stone is projected vertically upward from the ground with a speed of 10 m s then it s g 10 m s 1 Potential energy will be maximum after 0 5 s 2 Kinetic energy will be maximum again after I s 3 Kinetic energy potential energy at a height of 2 5 m from the ground 4 Potential energy will be minimum after I s

12 Two similar springs P and Q have spring constants kp and ko such that kp ko They are stretched first by the same amount case a then by the same force case b The work done by the springs Wp and Wo are related as in case a and case b respectively 1 Wp WQ Wp Wo WQ 2 Wp WQ Wp 3 Wp WQ Wp Wo 4 Wp WQ Wp Wo

A rigid body moves a distance of 10 m along a straight line under the action of a force of 5N If the work done by this force on the body is 25 Joules the angle which the force makes with the direction of motion of the body is 1 0 2 30 3 60 4 90

The length of a rectangular plate is measured by a meter scale and is found to be 10 0 cm Its width is measured by Vernier callipers as 1 00 cm The least count of the meter scale and Vernier callipers are 0 1 cm and 0 01 cm respectively Maximum permissible error in area measured is 1 0 2 cm 3 0 3 cm 2 0 1 cm 4 Zero

5 The mass of a body measured by a physical balance in a lift at rest is found to be m If the lift is going up with an acceleration a its mass will be measured as 1 m 1 2 2 m 1 3 m 4 Zero

Two blocks of masses m 1kg and m 2kg are connected by a spring of constant k 100 N m and placed over a plank as shown The coefficient of friction between m and plank is 0 5 and there is no friction between m and plank Initially the whole system is at rest The plank is now pulled to right with constant acceleration a 2 m s Find the amplitude in cm of oscillation of block m relative to plank 2 m moooo m a 2m s

A 1 Kg slider moves along the smooth semi circular wire in a vertical plane as shown The spring constant is 2000N m and underformed length of 6 cm Distance d 16 cm If the slider is released from rest from position D determine the velocity of slider at position A g 10m s Pis d 16 cm b 6 cm

A car of mass 1000 kg moves on rough road where road friction is 10 percent of its weight and air friction is 2 percent of its weight To keep the car moving at constant speed of 36 km h 1 the power required is O 11 76 kW O 18 32 kW O 9 31 kW 7 52 kW

One end of a spring of negligible unstretched length and spring constant k is fixed at the origin 0 0 A point particle of mass m carrying a positive charge q is attached at its other end The entire system is kept on a smooth horizontal surface When a point dipole p pointing towards the charge q is fixed at the origin the spring gets stretched to a length and attains a new equilibrium position see figure below If the point mass is now displaced slightly by from its equilibrium position and released it is found to oscillate at frequency Ik m The value of is

Fig shows a circular surface and a parabolodial surface It is placed in a uniform electric field of magnitude E such that the circular surface is oriented at right angles to the direction of field Electric flux through the parabolodial surface is A zero C r E 1 B zr E D Tr E

given by U kx for x 0 and U 0 for x 20 If total mechanical energy of the particle is E its speed at x 1 Zero 2E is 2 2E mass m LE LU

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 4 Mg k 2 Mg k Mg k

A small mass m is placed and released from the vertical portion of a quarter circular arc as shown in figure As it slides the acceleration of the mass M on the smooth horizontal surface Continuously increases Continuously decreases First increases then decreases First decreases then increases M m R Smooth C 1 1 1 1

En escalator is used to move 5 people 60 kg each per minute from the first floor of a department store to the second floor 20 m bove Neglecting friction calculate the power in kW required

i With the increase in the weight of an object the pressure a increases b decreases c is not affected d none of these ii One Pascal is the pressure produced by a force of 1 dyne on 1 cm b force of 1 N on 1 m c force of 1 dyne on 1 m d force of 1 N on 1 cm iii At a given depth liquid exerts pressure a towards the sides of the vessel b towards the base of the vessel c towards the top of the vessel d in all directions iv There are two similar beakers A and B The beaker A is filled with water anc beaker B is filled with brine solution The pressure of water at the base of beaker A is a less than beaker B b more than beaker B fol omo hool

concern similar situations 14 A golf ball having a mass of 50g and a momentum of 5kg m s approaches a stationary bowling ball having a mass of 7kg The golf ball hits the bowling ball head on and sticks to it What is the speed of the bowling ball golf ball combination after the collision assuming no external forces are acting a 0 61 m s b 1 23 m s c 0 71 m s d 2 4 m s e 1 8 m s 5 kg m s before collision after collision

e where e is the coefficient of restitution then A particle of mass m collides head on with a stationary particle of mass m2 If m m1 will return back m1 will move in same direction O m1 will stop unpredictable

A chain of mass m length is suspended from a point O Now the midpoint P of the chain is also taken slowly put at point O Find the work done by gravity in this process O 3mg 16 O 9mg 40 O 5mg 16 07mg 0000000000000000 Pam

A sphere A of mass 2kg moving with velocity Vo collide with bob of mass 1kg as shown in the figure value of tension at which string of pendulum break is 40N If length of pendulum is 30cm then find the maximum value of vo in m s so that string does not break Coefficient of restitution is 1 2 10 A B 2m m N

A lift motor has to move a fully loaded lift 6m between floors in 8 5s The lift has a mass of 1900kg ignore friction a What is the work done by the motor in joules b What is the minimum power in watt of the motor to raise the lift at a steady speed

A particle is projected with a velocity 20 m s from bottom of inclined smooth fixed plane of inclinatic 300 and height 10 m If the maximum height in m from ground reached by the particle is H Find 2 5 20m s 30 10m

The diagram shows three arrangement circular loops centered on vertical axes carrying identical currents in the direct indicated Rank the arrangements accordin the magnitude of the magnetic field at midpoints between the loops on the cer axes from minimum to maximum 00 00 00 2 1 1 2 3 2 2 3 1 3 2 1 3 4 3

A particle of mass M initially at rest is split into 1 1 1 three parts of masses in the ratio of The 3 1 V 2 7 4 4 2 first two masses move perpendicular to each other with a speed V and 2V along y axis and x axis respectively Calculate the speed of the third particle

Two springs of force constants K and K respectively are connected to a mass m as shown The frequency of oscillation of the mass is f if both K and K are made four times their original values the frequency of oscillation becomes A B C K Foo f 2 f 4 4f K 00004 My Answer