## NEET AIPMT Physics Chapter Wise Solutions -Work, Energy and Power

NEET AIPMT Physics Chapter Wise SolutionsBiology Chemistry

**1. Two particles A and B, move with constant velocities and. At the initial moment their position vectors are and respectively. The condition for particles A and B for their collision is**

**2. The heart of a man pumps 5 litres of blood through the arteries per minute at a pressure of 150 mm of mercury. 13.6 x 10 ^{3 }kg/m^{3} and g=10 m/s^{2} then the power **

^{ }(a) 3.0

(b) 1.50

(c) 1.70

(d) 2.35

**(AlPMT 2015)**

**3. A ball is thrown vertically downwards from a height of 20 m with an initial velocity VQ. It collides with the ground, loses 50 percent of its energy in collision and rebounds to the same height. **

The initial velocity V0 is (Take g = 10 ms^{-2})

(a) 28 ms^{-1}

(b) 10 ms^{-1
}(c) 14 ms^{-1}

(d) 20 ms^{-1} **(AlPMT 2015)**

**4. 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 θ to its initial direction and has a speed The second block’s speed after the collision is**

**5. 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**

**6. A block of mass 10 kg, moving in x direction with a constant speed of 10 m s ^{-1}, is subjected to a retarding force F = 0.l x J/m during its travel from x = 20 m to 30 m. Its final KE will be**

(a) 275 J

(b) 250 J

(c) 475 J

(d) 450 J

**(AlPMT 2015, Cancelled)**

**7. Two particles of masses m _{1,} m2 move with initial velocities u_{1}and u2. On collision, one of the particles get excited to higher level, after absorbing energy e. If final velocities of particles be v_{1} and v2 then we must have**

**8. Two similar springs P and Q have spring constants KP and KQ, such that KP> KQ. 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 WQ are related as. in case**

(a) and case

(b) respectively

(a) Wp>WQ;WQ>Wp

(b) Wp<WQ;WQ<Wp **(AlPMT 2015, Cancelled)**

**9. 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**

(a) mv^{2}

(b) mv^{2}

(c) 2mv^{2}

(d) 4mv^{2}**(AIPMT 2014)**

**10. A uniform force of (3 + ) newton acts on a particle of mass 2 kg. Hence the particle is displaced from position (2 + ) meter to position (4 + 3 – ) meter. The work done by the force on the particle is**

(a) 13 J

(b) 15 J

(c) 9J

(d) 6J **(NEET 2013)**

**11. A particle with total energy E is moving in a potential energy region U(x). Motion of the particle is restricted to the region when**

**12. One coolie takes 1 minute to raise a suitcase through a height of 2 m but the second coolie takes 30 s to raise the same suitcase to the same height. The powers of two coolies are in the ratio**

(a) 1: 3

(b) 2 :1

(c) 3:1

(d) 1:2 **(Karnataka NEET2013)**

**13. The potential energy of a particle in a force field is where A and B are positive constants and r is the distance of particle from the centre of the field. For stable equilibrium, the distance of the particle**

**14. A solid cylinder of mass 3 kg is rolling on a horizontal surface with velocity 4 m s ^{-1}. It collides with a horizontal spring of force constant 200 N m^{-1}. The maximum compression produced in the spring will be**

(a) 0.5 m

(b) 0.6 m

(c) 0.7 m

(d) 0.2 m (

**Prelims 2012 )**

**15. Two spheres A and B of masses m _{1} and m_{1} respectively collide. A is at rest initially and B is moving with velocity v along x-axis. After collision B has a velocity in a direction perpendicular to the original direction. The mass A moves after collision in the direction**

**16. A car of mass m starts from rest and accelerates so that the instantaneous power delivered to the car has a constant magnitude P0. The instantaneous velocity of this car is proportional to**

**17. The potential energy of a system increases if work is done**

(a) upon the system by a nonconservative force.

(b) by the system against a conservative force.

(c) by the system against a nonconservative force.

(d) upon the system by a conservative force.** (Prelims 2011)**

**18. A body projected vertically from the earth reaches a height equal to earth’s radius before returning to the earth. The power exerted by the gravitational force is greatest**

(a) at the highest position of the body.

(b) at the instant just before the body hits the earth.

(c) it remains constant all through.

(d) at the instant just after the body is projected. **(Prelims 2011)**

**19. A particle of mass m is released from rest and follows a parabolic path as shown. Assuming that the displacement of the mass from the origin is small, which graph correctly depicts the position of the particle as a function of time?**

**20. Force Fon a particle moving in a straight line varies with distance d as shown in figure.**

The work done on the particle during its displacement of 12 mis

(a) 18 J

(b) 21J

(c) 26 J

(d) 13 J **(Prelims 2011)**

**21. A mass m moving horizontally (along the x-axis) with velocity v collides and sticks to a mass of 3m moving vertically upward (along the v-axis) with velocity 2v. The final velocity of the combination is**

**22. A ball moving with velocity 2 m/s collides head on with another stationary ball of double the mass. If the coefficient of restitution is 0.5, then their velocities (in m/s) after collision will be**

(a) 0,1

(b) 1,1

(c) 1,0.5

(d) 0,2 **(Prelims 2010)**

**23. 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?**

(a) 400W

(b) 200W

(c) 100 W

(d) 800 W **(Prelims 2010)**

**24. A particle of mass M, starting from rest, undergoes uniform acceleration. If the speed acquired in time T is V, the power delivered to the particle is**

**25. 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**

(a) 2Mg/ k

(b)4Mg//k

(e) Mg/2k

(d) Mg/k **(Prelims 2009)**

**26. A body of mass 1 kg is thrown upwards with a velocity 20 m/s. It momentarily comes to rest after attaining a height of 18 m. How much energy is lost due to air friction? (g = 10 m/s ^{2})**

(a) 30 J

(b) 40 J

(c) 10 J

(d) 20 J

**(Prelims 2009)**

**27. 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 8 ms**

^{-1}. If the third part flies off with a velocity of 4 ms^{-1}, its mass would be(a) 7 kg

(b) 17 kg

(e) 3 kg

(d) 5 kg

**(Prelims 2009)**

**28. An engine pumps water continuously through a hose. Water leaves the hose with a velocity v and m is the mass per unit length of the water jet. What is the rate at which kinetic energy is imparted to water?**

**29. A shell of mass 200 gm is ejected from a gun of mass 4 kg by an explosion that generates 1.05 kJ of energy. The initial velocity of the shell is**

(a) 40 ms^{-1
}(b) 120 ms^{-1}

(c) 100 ms^{-1}

(d) 80 ms^{-1} **(Prelims 2008)**

**30. 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 energy. How much power is generated by the turbine ? (g – 10 m/s ^{2})**

(a) 12.3 kW

(b) 7.0 kW

(c) 8.1 kW

(d) 10.2 kW

**(Prelims 2008)**

**31. A vertical spring with force constant k is fixed on a table. A ball of mass m at a height h above the free upper end of the spring falls vertically on the spring so that the spring is compressed by a distance d. The net work done in the process is**

**32. 300 J of work is done in sliding a 2 kg £lock up an inclined plane of height 10 m. Work done against friction is (Take g = 10 m/s ^{2})**

(a) 1000 J

(b) 200 J

(c) 100 J

(d) zero.

**(2006)**

**33. The potential energy of a long spring when stretched by 2 cm is U. If the spring is stretched by 8 cm the potential energy stored in it is**

(a) 674

(b) 4U

(c) 86/

(d) 1667 **(2006)**

**34. A body of mass 3 kg is under a constant force which causes a displacement s in metres in it, 1 2 given by the relation , where t is in seconds.**

**35. 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**

(a) 324 J

(b) 486 J

(c) 256 J

(d) 524 J.

**(2005)**

**36. A force F acting on an object varies with distance x as shown here. The force is in N and x in m. The work done by the force in moving the object from x = 0tox=6mis**

(a) 18.0 J

(b) 13.5 J

(c) 9.0 J

(d) 4.5 J. **(2005)**

**37. A particle of mass m _{1} is moving with a velocity V_{1 }and another particle of mass m2 is moving with a velocity v2. Both of them have the same momentum but their different kinetic energies are**

**38. A ball of mass 2 kg and another of mass 4 kg are dropped together from a 60 feet tall building. After a fall of 30 feet each towards earth, their respective kinetic energies will be in the ratio of**

(a) 72:1

(b) 1 : 4

(c) 1 : 2

(d) 1: >/2** (2004)**

**39. A mass of 0.5 kg moving with a speed of 1.5 m/s on a horizontal smooth surface, collides with a nearly weightless spring of force constant k = 50 N/m. The maximum compression of the spring would be**

(a) 0.15 m

(b) 0.12 m

(c) 1.5 m

(d) 0.5 m **(2004)**

**40. When a long spring is stretched by 2 cm, its potential energy is U. If the spring is stretched by 10 cm, the potential energy stored in it will be**

(a) U/5

(b) 5U

(c) 10U

(d) 25U **(2003)**

**41. A stationary particle explodes into two particles of masses m _{1} and m2 which move in opposite directions with velocities v_{1} and v2. The ratio of their kinetic energies E_{1/}E2 is**

(a) m2/m

_{1}

(b) m

_{1}/m2

(c) 1

(d) m

_{1}v2 /m2v

_{1}

**(2003)**

**42. If kinetic energy of a body is increased by 300% then percentage change in momentum will be**

(a) 100%

(b) 150%

(c) 265%

(d) 73.2%. **(2002)**

**43. A child is sitting on a swing. Its minimum and maximum heights from the ground 0.75 m and 2 m** **respectively, its maximum speed will be**

(a) 10 m/s

(b) 5 m/s

(c) 8 m/s

(d) 15 m/s. **(2001)**

**44. Two springs A and B having spring constant KA and KB (KA = 2KB) are stretched by applying force of equal magnitude. If energy stored in spring A is E, then energy stored in B will be**

**45. A particle is projected making an angle of 45° with horizontal having kinetic energy K. The kinetic energy at highest point will be**

**46. If = (60+15 -3 )N and = (2 -4 + 5 ) m/s, then instantaneous power is**

(a) 195 watt

(b) 45 watt

(c) 75 watt

(d) 100 watt. **(2000)**

**47. A mass of 1 kg is thrown up with a velocity of 100 m/s. After 5 seconds, it explodes into two parts. One part of mass 400 g comes’down with a velocity 25 m/s. The velocity of other part is (Take g = 10 ms ^{-2})**

(a) 40 m/s↑

(b) 40 m/s ↑

(c) lOOm/s↑

(d) 60 m/s ↑

**(2000)**

**48. Two bodies with kinetic energies in the ratio of 4 : 1 are, moving with equal linear momentum. The ratio of their masses is**

(a) 4 : 1

(b) 1 : 1

(c) 1 : 2

(d) 1 : 4. **(1999)**

**49. Two equal masses m _{1} and m_{2} moving along the same straight line with velocities + 3 m/s and -5 m/s respectively collide elastically. Their velocities after the collision will be respectively**

(a) – 4 m/s and +4 m/s

(b) +4 m/s for both

(c) – 3 m/s and +5 m/s

(d) – 5 m/s and + 3 m/s.

**(1998)**

**50. A force acts on a 3 g particle in such a way that the position of the particle as a function of time is given by x = 3t – 4t ^{2} + t^{3}, where x is in metres and t is in seconds. The work done during the first 4 second is**

(a) 490 mJ

(b) 450 mJ

(c) 576 mJ

(d) 530 mJ.

**(1998)**

**51. A shell, in flight, explodes into four unequal parts. Which of the following is conserved?**

(a) Potential energy

(b) Momentum

(c) Kinetic energy

(d) Both (a) and (c). ** (1998)**

**52. Two bodies of masses m and 4 m are moving with equal kinetic energies. The ratio of their linear momenta is**

(a) 1 : 2

(b) 1 : 4

(c) 4:1

(d) 1 : 1. **(1998, 97, 89)**

**53. A metal ball of mass 2 kg moving with speed of 36 km/h has a head on collision with a stationary ball of mass 3 kg. If after collision, both the balls move as a single mass, then the loss in K.E. due to collision is**

(a) 100J

(b) 140 J

(c) 40 J

(d) 60 J. **(1997)**

**54. A body moves a distance of 10 m along a straight line under the action of a 5 N force. If the work done is 25 J, then angle between the force and direction of motion of the body is**

(a) 60°

(b) 75°

(c) 30°

(d) 45°.** (1997)**

**55. A moving body of mass m and velocity 3 km/hour collides with a rest body of mass 2m and sticks to it. Now the combined mass starts to move. What will be the combined velocity?**

(a) 3 km/hour

(b) 4 km/hour

(c) 1 km/hour

(d) 2 km/hour. **(1996)**

**56. The potential energy between two atoms, in a molecule, is given by U(x) = – ****where and b are positive constants and x is the distance between the atoms. The atom is in stable equilibrium, when**

**57. A body, constrained to move in v-direction, is subjected to a force given by =(-2+15+6)N The work done by this force in moving the body through a distance of 1 Oj m along y-axis is**

(a) 150 J

(b) 20 J

(c) 190 J

(d) 160 J. **(1994)**

**58. The kinetic energy acquired by a mass m in travelling distance d, starting from rest, under the action of a constant force is directly proportional to**

(a) m

(b) m°

(c)

(d)1/ **(1994)**

**59. A position dependent force, F = (7 – 2x + 3x ^{2}) N acts on a small body of mass 2 kg and displaces it from x = 0 to x = 5 m. The work done in joule is**

(a) 135

(b) 270

(c) 35

(d) 70.

**(1994, 92)**

**60. When a body moves with a constant speed along a circle**

(a) no work is done on it

(b) no acceleration is produced in it

(c) its velocity remains constant

(d) no force acts on it. **(1994)**

**61. Two identical balls A and B collide head on elastically. If velocities of A and B, before the collision, are + 0.5 m/s and – 0.3 m/s respectively, then their velocities, after the collision, are respectively**

(a) – 0.5 m/s and + 0.3 m/s

(b) + 0.5 m/s and + 0.3 m/s

(c) + 0.3 m/s and – 0.5 m/s

(d) – 0.3 m/s and + 0.5 m/s. **(1994, 91)**

**62. Two masses of 1 g and 9 g are moving with equal kinetic energies. The ratio of the magnitudes of their respective linear momenta is**

(a) 1 : 9

(b) 9 : 1

(c) 1:3

(d) 3: 1 **(1993)**

**63. A particle of mass M is moving in a horizontal circle of radius R with uniform speed v. When it moves from one point to a diametrically opposite point, its**

(a) kinetic energy change by Mv^{2}/4

(b) momentum does not change

(c) momentum change by 2Mv .

(d) kinetic energy changes by Mv^{2} **(1992)**

**64. How much water a pump of 2 kW can raise in one minute to a height of 10 m ? (take g = 10 m/s ^{2})**

(a) 1000 litres

(b) 1200 litres

(c) 100 litres

(d) 2000 litres

**(1990)**

**65. A bullet of mass 10 g leaves a rifle at an initial velocity of 1000 m/s and strikes the earth at the same level with a velocity of 500 m/s. The work done in joule overcoming the resistance of air will be**

(a) 375

(b) 3750

(c) 5000

d) 500 **(1989)**

**66. The coefficient of restitution e for a perfectly elastic collision is**

(a) 1

(b) 0

(c) ∞

(d) -1 **(1988)**

**Explanations**