Work, power & energy Questions and Answers

A simple pendulum of length is oscillating with amplitude 0 At some instant it makes angle 0 with the vertical its speed of the bob is v The acceleration of bob will be A g sin 0 B g tan 0 sin 0 G C g sin 0

2 4 A bicyclist comes to a skidding stop in 10 m During this process force on the bicycle due to the road is 200N and is directly opposed to motion The work done by the cycle on the road is a 2000 b 200J c zero Thinking Process d 20 000

25 A long spring when stretched by a distance x has potential energy U On increasing the stretching to nx the potential energy of the spring will be U a n c n U b nu d n c Zero Tim 1 T 2n 177 2 Simple per

A water pump lifts water at the rate of 5 litre per second through an average height of 8 m from a well of depth 12 m Its power will be O 1280 watt O 980 watt O 1180 watt O 1080 watt

d 2 cos it A 3 13 Figure 14 26 a shows a spring of force constant k clamped rigidly at one end and a mass m attached to its free end A force F applied at the free end stretches the a mass m at either end Each end of the spring in Fig 14 26 b is stretched by the spring Figure 14 26 b shows the same spring with both ends free and attached to same force F a b k a TTL F F m com time of m k Com b m at nor net bay F Fig 14 26 What is the maximum extension of the spring in the two cases If the mass in Fig a and the two masses in Fig b are released what is the 900 2 plitude

Three charges lie along the x axis The positive charge q1 15 uC is at x 2 0 cm and the positive charge q2 6 0 C is at the origin Where must a negative charge q3 be placed on the x axis so that the resultant electric force on it is zero B Name an application of part A in the real world and draw a diagram

3 4E 3 3R The grid each square of 1 m x 1 m represents a region in space containing a uniform electric field If potentials at point O A B C D E F G H are respectively 0 1 2 1 2 0 1 1 and 0 volts Find the electric field intensity y O C 1 V m 2 1 i V m 3 i 1 V m 4 i i V m CE G A 1m H TI F BX

32 3 9 6 N 3m 1 8N 2 6N 3 3N 4 zero A bicycle is moving with constant acceleration The frictional force on rear wheel is 1 Zero 2 In forward direction 3 Backward direction 4 All of these AJKOT CENTER 0 m 1 mgl sine 2 mgl cos0 3 mgl 1 cose 4 mgl 1 cose Work done to carry bob upto angle 0 with the vertical very slowly from initial vertical position is 12 N 77

9 A particle undergoing simple harmonic motion has time dependent displacement TI given by x t A sin The ratio of kinetic 90 to potential energy of this particle att 210s will be JEE Main 2019 11 Jan Shift 1 a 2 b 1 c 1 2 9 d 3 10 29 pm

nless axis N 0 and n e 3 83 Two blocks of masses m 1 kg and m 2 kg are connected by non deformed light spring They are lying on a rough horizontal surface The coefficient of friction between the blocks and the surface is 0 4 What minimum constant force F has to in be applied in horizontal direction to the block of mass m order to shift the other block Take g 10 m s F m 6oooooooood m A 8N C 10N Figure 3 107 B 15 N D 25 N 2 snoda bila ia

to is of d 0 3 15 A body with mass 2 kg moves in one direction in presence of a force which is described by the potential energy graph If the body is released from rest at x 2 m then its speed when it crosses x 5 m is A Zero C 2 ms U joule 10 1 2 3 3 5 4 4 5 5 x meter Figure 3 83 B 1 ms D 3 ms 1

3 101 The following figure 3 116 illustrates the relation between the position of a particle and force The work done in displacing the particle from x 1 to 5 m is Force in N A 20 joules C 70 joules 20 10 0 10 20 2 3 14 5 Figure 3 116 Xin m B 60 joules D 100 joules

3 80 A block of mass 1 kg is attached to one end of a spring of force constant k 20 N m The other end of the spring is attached to a fixed rigid support This spring block system is made to oscillate on a rough horizontal surface u 0 04 The initial displacement of the block from the equilibrium position is a 30 cm How many times the block passes from the mean position before coming to rest Take g 10 m s B 7 D 15 A 11 C 6

6 A small block A of mass m is given a velocity v in horizontal direction as shown The bigger block B is initially at rest The curved surface of the block B becomes vertical at the top point If M 4m what should be the minimum value of v so that the block A climbs upto the top on B All surfaces are smooth g 10 m s 90 4 m A 1 20 m s m v B M 2 10 m s 4 2 m s

A body constrained to move along y axis is subjected to a constant force F 1 2 3kN The work done by this force in moving the body a distance of 4 m along y axis is b 8 J a 4 c 12 d 24 J

3 39 A block of mass 1 kg slides down a curved track from rest that is one quadrant of a circle of radius 1 m Its speed at the bottom is 2 m s The work done by frictional force is A 8 J C 4J R 1 m Figure 3 93 B 8 J D 4 J P