work energy and power class 11 numericals with solutions

 Dear students in this page contains work energy and power class 11 numericals with solutions pdf. It also contains pdf for neet questions of chapter 6 work energy and power 11 jee questions, aiims important questions at one place to get you all prepared for your neetaiims ,jee main, advance exams as well as cbse board exams and other board exams. Visit my nawendu classes youtube channel for more help.

work energy and power

1. If momentum is increased by 20% then kinetic energy increased by 
    AFMC 1997 
Answer- 44%
2. If the momentum of a body is increased by 50% , then the percentage increase in its kinetic energy is 
   CBSE AIPMT 1995 
Answer- 125%
3. If the kinetic energy of a body is increased by 300% , then the percentage change in its momentum will be
   CBSE AIPMT 2002 
Answer- 100%
4. The mass of two substances are 25g and 81g respectively. If their kinetic energies are same then the ratio of their momentum is  
    AFMC 2000 
Answer- 5:9
5. Two bodies of masses ‘m’ and ‘4m’ are moving with equal kinetic energy. Then the ratio of their linear momentum will be   
    AIIMS 1999 
Answer- 1:2
6.Two bodies with kinetic energies in the ratio 4:1 are moving with equal linear momentum. The ratio of their masses is  
    CBSE AIPMT 1999 
Answer- 1:4
7. A stationary particle explodes into two particles of masses \[{{m}_{1}}\]and ${{m}_{2}}$,which move in opposite directions with velocities ${{v}_{1}}$and ${{v}_{2}}$.The ratio of their kinetic energies$\frac{{{E}_{1}}}{{{E}_{2}}}$ IS        
    CBSE AIPMT 2003 
Answer-  $\frac{{{m}_{2}}}{{{m}_{1}}}$
8.If a man increases his speed by 2m/s, his Kinetic energy is doubled. The original speed of the man is
Answer- $\left( 2+2\sqrt{2} \right)m/s$ 
9.A body is displaced from $x={{x}_{1}}$ to $x={{x}_{2}}$ by a force 2x. The work done is  
    CPMT 1993  
Answer- $x_{2}^{2}-x_{1}^{2}$ 
10.A particle moves from a point (-2i+5j) to (4j+3k) when a force of (4i+3j) N is applied. How much work has been done by the force ?
Answer- 5J
11.A position dependent force, \[~F=\text{ }\left( 7-2x+3{{x}^{2}} \right)\]N acts on a small body of mass 2 kg and displaces it from x =0 to x=5 m. Work done in joule is
   CBSE AIPMT 1992 
Answer- 135
12. A uniform force of $\left( 3\hat{i}+\hat{j} \right)N$ acts on a particle of mass 2 kg. Hence, the particle is displaced from position $\left( 2\hat{i}+\hat{k} \right)m$ to position $\left( 4\hat{i}+3\hat{j}-\hat{k} \right)m$. The work done by the force on the particle is      
    NEET 2013 
Answer-  9J
13.A body of mass 5kg has momentum of 10kg m/s. When a force of 0.2N is applied on it for 10s, the change in its kinetic energy is  
      AIIMS 2000 
Answer- 4.4J
14. If a body of mass 3kg is dropped from the top of a tower of height 25m. Then its kinetic energy after 3 sec is
    AFMC 1998 
Answer- 735J
15.   The particle of 50 kg is at rest. The work done to accelerate it by 20m/s in 10 s is 
   AIIMS 2012 
Answer-  ${{10}^{4}}$J 
16.A block of mass 10kg is moving in x-direction with a constant speed of 10 m/s. It is subjected to a retarding force F=-0.1 x joule/meter during its travel from x=20 meter to x=30 meter. Its final kinetic energy will be  
     AIIMS 2005 
Answer- 475J
17.A particle of mass 10g is thrown vertically upwards with a speed of 5 m/s. The work done by the force of gravity during the time the particle goes up is 
    AIEEE 2006  
Answer- 0.125J
18.  A  ball is released from the top of a tower ,the ratio of work done by force of gravity in first ,second and third second of the motion of the ball is 
   AIIMS 2005 
Answer- 1:3:5
19.  A  spherical ball of mass 20kg is stationary at the top of a  hill of height 100m. It rolls down a smooth surface to the ground ,then climbs up another hill of height 30m and finally rolls down to a horizontal base at a height of 20m above the ground. The velocity attained by the ball is 
   AIIMS 2006 
Answer- 40m/s
20.  A bullet of mass m moving with velocity v strikes a suspended wooden lock of mass M. If the block rises to a height h ,the initial velocity of the block will be
   AIIMS 2013 
Answer- \[\sqrt{2gh}\] 
21.  A body of mass 5 kg is raised vertically to a height of 10 m by a force of 170 N .The velocity of the body at this height will be 
  AIIMS 1998 
Answer-   22m/s
22. A body of mass 3kg is under a constant force, which causes a displacement s in metre in it,given by the relation s=$\frac{1}{3}{{t}^{2}}$ , where t is in second ,work done by the force in 2s is 
    CBSE AIPMT 2006 
Answer-  8/3 joule 
23. A body of mass 2kg is projected vertically upwards with speed of 3m/s. The maximum gravitational potential energy of the body is 
Answer- 9J
24. If a water falls from a dam into a turbine wheel 19.6 below, then the velocity of water at the turbines is (take g=9.8m/s2 )
      AIIMS 2007 
Answer- 19.6m/s
25.A body of mass 1 kg is thrown upwards with a velocity 20 m/s. It momentarily comes to rest after attending a height of 18m. How much energy is loss due to air friction (g=10m/s2)
   CBSE AIPMT 2009 
Answer- 20J
26. 300J of work is done in sliding a 2kg block up an inclined plane of height 10m.Taking g=10 $m/{{s}^{2}}$,work done against friction is 
   CBSE AIPMT 2006 
Answer-  100 joule 
27. Two springs of spring constant 1500 N/m and 3000 N/m respectively are stretched with the same force. They will have the potential energies in the ratio of  
     AFMC 2000 
Answer- 2:1
 28. A spring of force constant 10 N per meter has an initial has an initial stretch 0.20 m. In changing the stretch to 0.25m, the increase in potential energy is about 
Answer- 0.1
29. A spring of spring constant 5 x 103 N/m is stretched initially by 5cm from the unscratched position. Then the work required to stretch it further by another 5 cm is
     AIEEE 2003 
Answer- 18..75Nm
30.   A spring 40mm long is stretched by applying a force . If10 N force is required to stretched the spring through 1mm,then work done in stretching the spring through 40mm is
   AIIMS 2001 
Answer-   8J
31. A car is moving with constant speed of 20 m/s against a resistance of 100N. The power exerted by the car is 
Answer- 2KW
32. An electric motor creates a tension of 4500N in a hoisting cable and reels it at the rate of 2 m/s. What is the power of the electric motor 
Answer- 9KW
33. How much water, a pump of 2kw can rise in one minute to height of 10m, taking g=10 m/s2  
  CBSE AIPMT 1990 
Answer- 1200 liters
34. Water falls from a height of 60m at the rate of 15kg/s to operate a turbine. The losses due to frictional force are 10% of energy. How much power is generated by the turbine? (g=10 m/s2 )
Answer- 8.1KW
35. 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 
       CBSE AIPMT 2015 
Answer-    $\sqrt{\frac{mk}{2}}{{t}^{\frac{-1}{2}}}$ 
36.A stone is tied to a string of length l and is whirled in a vertical circle with the other end of the string as the center .At a certain instant of time ,the stone is at its lowest position and has a speed u. The magnitude of the change in velocity as it reaches a position where the string is horizontal (g being acceleration due to gravity ) is
   CBSE AIPMT 2004 
Answer-  $\sqrt{2\left( {{u}^{2}}-gl \right)}$ 
 37.A uniform chain of length 2m is kept on a table such that a length of 60cm hangs freely from the edge of the table. The total mass of the chain is 4 kg. What is the work done in pulling the entire chain on the table ? 
    AIEEE 2004 
Answer- 3.6J
38.A block of mass m moving with speed v collides with another block of mass 2m at rest. The lighter block comes to rest after collision. What is the value of coefficient of restitution 
Answer- 1/2
39. A body of mass 10kg and velocity 10m/s collides with a stationary body of mass 5kg. After collision both bodies stick to each other, velocity of the bodies after collision will be. 
     AFMC 1997 
Answer- \[\frac{20}{3}m{{s}^{-1}}\] 
40.  Two identical balls A and B having velocities of 0.5m/s and -0.3m/s respectively collide elastically in one dimension. The velocities of B and A after the collision respectively will be 
    NEET 2016 
Answer-    -0.3m/s and 0.5m/s
41. A object of mass 40kg having velocity 4 m/s collides with another object m=60 kg having velocity 2 m/s. The collision is perfectly inelastic. The loss in energy is 
      AFMC 2001  
Answer- 48J
42.A ball moving with velocity 2m/s collides head on with another stationary ball of double the mass. If coefficient of restitution is 0.5, then their velocities after collision will be
    CBSE AIPMT 2010 
Answer- 0,1
43.A block of mass 0.5 kg is moving with a speed of 2.0m/s on smooth surface. It strikes another mass of 1.0kg and then they move together as a single body. The energy loss during collision is
    AIEEE 2008 
Answer- 0.67J
44.A ball falls under gravity from height 10 m with an initial velocity u. It hits the ground, loss 50% of the energy in collision and it rises to the same height. What is the value of u 
Answer- 14m/s
45. A ball is thrown vertically downwards from a height of 20m with an initial velocity \[{{v}_{0}}\] .It collides with the ground, loses 50% of its energy in collision and rebounds to the same height. The initial velocity \[{{v}_{0}}\] is (take g= 10 $m{{s}^{-2}}$)
       CBSE AIPMT 2015 
Answer-   20m/s
46. A force F acting on an object varies with distance x as shown here. The  force is in newton and x is in metre. The work done by the force in moving the object from x=0 to x=6m is          
    CBSE AIPMT 2005 
A force F acting on an object varies with distance x as shown here. The  force is in newton and x is in meter

Answer-  13.5J
47.  A body of mass 1 kg is thrown upwards with a velocity 20m/s. It momentarily comes to rest after attaining a height of 18 m. How much energy is lost due to air friction 
    CBSE AIPMT 2009 
Answer-  20 joule 
48.  Consider a drop of rain water having mass 1g falling from a height of 1km. It hits the ground with a speed of 50m/s. Take g constant with a value of 10 $m/{{s}^{2}}$. The work done by (i) gravitational force and the (ii) resistive force of air is 
   NEET 2017 
Answer-   (i) 10 J (ii)  -8.75 J
49.  A block of mass M is attached to the lower end of a vertical spring .The spring is hung from a ceiling and has force constant value k. The mass is released from rest with the spring initially unstretched . The maximum extension produced in the length of the spring will be 
    CBSE AIPMT 2009 
Answer-   $\frac{2Mg}{k}$ 
50. The potential energy of a particle in a force field is  $U=\frac{A}{{{r}^{2}}}-\frac{B}{r}$  ,where A and B are positive constants and r is the distance of particle from the center of the field. For stable equilibrium ,the distance of the particle is
    CBSE AIPMT 2012 
Answer-  $\frac{2A}{B}$
51. On a frictionless surface, a block of mass M moving at speed v collides elastically with another block of same mass M which is initially at rest. After collision the first block moves at an angle $\theta $ to its initial direction and has a speed v/3.The second block’s after the collision is 
   CBSE AIPMT 2015 
Answer-   $\frac{2\sqrt{2}}{3}v$  
52. A particle of mass 10g moves along a circle of radius 6.4 cm with a constant tangential acceleration. What is the magnitude of this acceleration , if the kinetic energy of the particle becomes equal to $8\times {{10}^{-4}}$ J by the end of the second revolution after the beginning of the motion ?
    NEET 2016 
Answer-    $0.m/{{s}^{2}}$ 
53. What is the minimum velocity with which a body of mass m must enter a vertical loop of radius R so that it can complete the loop ?
     NEET 2016 
Answer-  $\sqrt{5gR}$ 
54.  A body of mass 1kg begins to move under the action of a time dependent force \[\vec{F}=\left( 2t\hat{i}+3{{t}^{2}}\hat{j} \right)N\],where $\hat{i}$and$\hat{j}$ are unit vectors along X and Y axes . What power will be developed by the force at the time t ?
   NEET 2016 
Answer-  $\left( 2{{t}^{3}}+3{{t}^{5}} \right)W$ 
55.   A person of mass 70 kg wants to loss 7 kg by moving up and down on the stairs of 12m height . Assume he burns twice as much fat while going up than going down. If 1 kg of fat is burnt on expending 9000kcal. How many times must he go up and down to reduce his 7kg weight ? 
   AIIMS 2016 
Answer-  $21\times {{10}^{3}}$ times
56.   The 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 particle by the force acting on it is    
   AIIMS 2017 
Answer-   $m{{k}^{2}}{{r}^{2}}t$
57. A time dependant force F=6t acts on a particle of mass 1 kg. If the particle starts fro rest ,the work done by the force during the first 1 s will be     
    IIT 2017 Main 
Answer-   4.5 J 
58. A block of mass 2kg is free to move along the x axis. It is at rest and from t=0 onwards it is subjected to a time dependent force $F\left( t \right)$ in the x direction .The force $F\left( t \right)$ varies with t as shown in the figure. The kinetic energy of the block after 4.5 s is    
   IIT 2010 
A block of mass 2kg is free to move alon

Answer-   5.06 J 
59. A uniform cable of mass M and length L is placed on a horizontal surface such that its (\[\frac{1}{n}\])th part is hanging below the edge of the surface. To lift the hanging part of the cable upto the surface, the work done should be
   IIT 2019 Main 9 April I  
Answer-   $\frac{MgL}{2{{n}^{2}}}$  
60. A block of mass m is kept on a platform which starts from rest with constant acceleration g/2 upwards as shown in figure. Work done by normal reaction on block in time t is
  IIT 2019 Main 10 Jan I 
A block of mass m is kept on a platform which starts from rest with constant acceleration g/2

Answer- $\frac{3m{{g}^{2}}{{t}^{2}}}{8}$   
 61. A force acts on 2kg object , so that its position is given as a function of time as x = 3t2+ 5. What is the work done by this force in first 5 seconds?
 IIT 2019 Main 9 Jan II 
Answer- 900 J
62. A particle is moving in a circular path of radius a under the action of an attractive potential energy $U=-\frac{k}{{{r}^{2}}}$ . Its total energy is 
  IIT 2018 Main 
 Answer- Zero 
63. When a rubber band is stretched by a distance x, it exerts a restoring force magnitude $F=ax+b{{x}^{2}}$ , where a and b are constants. The work done in stretching the upstretched rubber band by L is 
 IIT 2014 Main  
Answer- $\frac{a{{L}^{2}}}{2}+\frac{b{{L}^{3}}}{3}$   

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