## NEET AIPMT Physics Chapter Wise Solutions – Laws of Motion

NEET AIPMT Physics Chapter Wise SolutionsChemistryBiology

**1. Two stones of masses m and 2m are whirled in horizontal circles, the heavier one in a radius and the lighter one in radius r/2. The tangential speed of lighter stone is n times that of the value of heavier stone when they experience same centripetal forces. The value of n is**

(a) 4

(b) 1

(c) 2

(d) 3 **(A1PMT 2015)**

**2. A plank with a box on it at one end is gradually raised about the other end. As the angle of inclination with the horizontal reaches 30°, the box starts to slip and slides 4.0 m down the plank in 4.0 s.**

The coefficients of static and kinetic friction between the box and the plank will be, respectively

(a) 0.5 and 0.6

(b) 0.4 and 0.3

(c) 0.6 and 0.6

(d) 0.6 and 0.5 **(AIPMT 24)15)**

**3. Three blocks A, B and C, of masses 4 kg, 2 kg and 1 kg respectively, are in contact on a ffictionless surface, as shown. If a force of 14 N is applied on the 4 kg block, then the contact force between A and B is**

**4.A block of m _{1} resets on a horizontal table.A light string connected to it passes over a frictionless pully at the edge of table and from its other end another block B of mass m2 is suspended. The coefficient of kinetic friction between the block and the table is pt. When the block A is sliding on the table, the tension**

**5. A system consists of three masses m _{1}, m2 and m3connected by a string passing over a pulley P. The mass m_{1} hangs freely and m2 and m3are on a rough horizontal table (the coefficient of friction = p). The pulley is ffictionless and of negligible mass. The downward acceleration of mass m_{1} is (Assume m1 = m2 = m3 = m)**

**6. The force F acting on a particle of mass m is indicated by the force-time graph Shown below. The change in momentum of the particle over %the time interval from zero to 8 s is**

(a) 24Ns

(b) 20Ns

(c) 12Ns

(d)6 Ns** (NEET 2013)**

**7. A balloon with mass m is descending down with an acceleration a (where a < g). How much mass should be removed from it so that it starts moving up with an acceleration a?**

**8. Three blocks with masses m, 2m and 3m are connected by strings, as shown in the figure. After an upward force F is applied on block m, the masses move upward at constant speed v. What is the net force on the block of mass 2ml (g is the acceleration due to gravity)**

(a) 3mg

(b) 6mg

(c) zero LimJ

(d) 2mg** (NEET 2013)**

**9. An explosion breaks a rock into three parts in a horizontal plane. Two of them go off at right angles to each other. The first part of mass 1 kg moves with a speed of 12 ms ^{-1} and the second part of mass 2 kg moves with 8 ms^{-1}**

**speed. If the third part flies off with 4 ms**

^{-1}speed, then its mass is(a) 7 kg

(b) 17 kg

(c) 3 kg

(d) 5 kg

**(NEET 2013)**

**10. The upper half of an inclined plane of inclination 0 is perfectly smooth while lower half is rough. A block starting from rest at the top of the plane will again come to rest at the bottom, if the coefficient of friction between the block and lower half of the ****plane is given by**

**11. A car is moving in a circular horizontal track of radius 10 m with a constant speed of 10 m/s. A bob is suspended from the roof of the car by a light wire of length 1.0 m. The angle made by the wire**

**12. A person holding a rifle (mass of person and rifle together is 100 kg) stands on a smooth surface and fires 10 shots horizontally, in 5 s. Each bullet has a mass of 10 g with a muzzle velocity of 800 ms ^{-1}. The final velocity acquired by the person and the average force exerted on the person are**

(a) -0.08 ms

^{-1},16N

(b) -0.8 ms

^{-1}, 8 N

(c) -1.6 ms

^{-1}, 16 N

(d) – 1.6 ms

^{-1},8 N

**(Karnataka NEET 2013)**

**13. A stone is dropped from a height h. It hits the ground with a certain momentum P. If the same stone is dropped from a height 100% more than the previous height, the momentum when it hits the ground will change by**

(a) 68%

(b) 41%

(c) 200%

(d) 100% **(Mains 2012)**

**14. A person of mass 60 kg is inside a lift of mass 940 kg and presses the button on control panel. The lift starts moving upwards with an acceleration 1.0 m/s ^{2}. If g = 10 m s^{-2,} the tension in the supporting cable is**

(a) 8600 N

(b) 9680 N

(c) 11000N

(d) 1200 N

**(Prelims 2011)**

**15. A body of mass M hits normally a rigid wall with velocity V and bounces back with the same velocity. The impulse experienced by the body is**

(a) MV

(b) 1.5MV

(c) 2MV

(d) zero **(Prelims 2011)**

**16. A conveyor belt is moving at a constant speed of 2 ms ^{1}. A box is gently dropped on it. The coefficient of friction between them is μ = 0.5. The distance that the box will move relative to belt before coming to rest on it, taking g = 10 ms^{-2}, is**

(a) 0.4 m

(b) 12 m

(c) 0.6 m

(d) zero

**(Mains 2011)**

**17. A block of mass m is in contact with the cart C as shown in the figure.**

**18. The mass of a lift is 2000 kg. When the tension in the supporting cable is 28000 N, then its acceleration is**

(a) 4 ms^{2} upwards

(b) 4 ms^{-2} downwards

(c) 14 ms^{-2}upwards

(d) 30 ms^{-2} downwards **(Prelims 2009)**

**19. A body, under the action of a force = 6 -8+ 10, acquires an acceleration of 1 m/s ^{2}. The mass of this body must be**

(a) 10 kg

(b) 20 kg

(c) 10 kg

**(Prelims 2009)**

**20.A roller coaster is designed such that riders experience “weightlessness” as they go round the top of a hill whose radius of curvature is 20 m. The speed of the car at the top of the hill is between**

(a) 16 m/s and 17 m/s

(b) 13 m/s and 14 m/s

(c) 14 m/s and 15 m/s

(d) 15 m/s and 16 m/s **(Prelims 2008)**

Three forces acting on a body are shown in the figure. To have the resultant force only along the y-direction, the magnitude of the minimum additional force needed is

**22. Sand is being dropped on a conveyer belt at the rate of M kg/s. The force necessary to keep the belt moving with a constant velocity of v m/s will be**

(a) newton

(b) zero

(c) Mv newton

(d) 2Mv newton **(Prelims 2008)**

**23. A block B is pushed momentarily along a horizontal surface with an initial velocity V. If ft is the coefficient of sliding friction between B and the surface, block B will come to rest after a time**

**24. A 0.5 kg ball moving with a speed of 12 m/s strikes a hard wall at an angle of 30° with the wall. It is reflected with the same speed at the same angle. If the ball is in contact with the wall for 0.25 seconds, the average force acting on the wall is**

(a) 96 N

(b) 48 N

(c) 24 N

(d) 12 N.** (2006)**

**25. A block of mass m is placed on a smooth wedge of inclination 0. The whole system is accelerated horizontally so that the block does not slip on the wedge. The force exerted by’the wedge on the block will be (g is acceleration due to gravity)**

(a) mgcos©

(b) wgsinO

(c) mg

(d) mg/cos0 **(2004)**

**26. The coefficient of static friction, ps, between block A of mass 2 kg and the table as shown in the figure is 0.2. What would be the maximum mass value of block B so that the two blocks do not move? The string and the pulley are assumed to be smooth and massless.**

**27. A man weighs 80 kg. He stands on a weighing scale in a lift which is moving upwards with a uniform acceleration of 5 m/s ^{2}. What would be the reading on the scale ? (g = 10 m/s^{2})**

(a) zero

(b) 400 N

(c) 800 N

(d) 1200 N

**(2003)**

**28. A monkey of mass 20 kg is holding a vertical rope. The rope will not break when a mass of 25 kg is suspended from it but will break if the mass exceeds 25 kg. What is the maximum acceleration with which the monkey can climb up along the rope ?(g = 10 m/s ^{2})**

(a) 5 m/s

^{2}

(b) 10 m/s

^{2}

(c) 25 m/s

^{2}

(d) 2.5 m/s

^{2}

**(2003)**

**29. A lift of mass 1000 kg which is moving with acceleration of 1 m/s ^{2}in upward direction, then the tension developed in string which is connected to lift is**

(a) 9800 N

(b) 10,800 N

(c) 11,000 N

(d) 10,000 N.

**(2002)**

**30. A block of mass 10 kg placed on rough horizontal surface having coefficient of friction μ = 0.5, if a horizontal force of 100 N acting on it then acceleration of the block will be**

(a) 10 m/s^{2}

(b) 5 m/s^{2}

(c) 15 m/s^{2}

(d) 0.5 m/s^{2}.** (2002)**

**31. 250 N force is required to raise 75 kg mass from a pulley. If rope is pulled 12 m then the load is lifted to 3 m, the efficiency of pulley system will be**

(a) 25%

(b) 33.3%

(c) 75%

(d) 90%. **(2001)**

**32. On the horizontal surface of a truck a block of mass 1 kg is placed (p = 0.6) and truck is moving with acceleration 5 m/sec ^{2} then the frictional force on the block will be**

(a) 5 N

(b) 6N

(c) 5.88 N

(d) 8 N. (2001)

** 33. A cricketer catches a ball of mass 150 gm in 0. 1 sec moving with speed 20 m/s, then he experiences force of**

(a) 300 N

(b) 30 N

(c) 3 N

(d) 0.3 N. **(2001)**

**34. A 1 kg stationary bomb is exploded in three parts having mass 1:1:3 respectively. Parts having same mass move in perpendicular direction with velocity 30 m/s, then the velocity of bigger part will be**

**35. A body of mass 3 kg hits a wall at, an angle of 60° and returns at the same angle. The impact time was 0.2 sec. The force exerted on the wall**

**36. Two masses as shown in the figure are suspended from a massless pulley. The acceleration of the system when masses are left free is**

**37. If the force on a rocket, moving with a velocity of 300 m/s is 210 N, then the rate of combustion of the fuel is**

(a) 0.07 kg/s

(b) 1.4 kg/s

(b) 0.7 kg/s

(d) 10.7 kg/s **(1999)**

**38. A mass of 1 kg is suspended by a thread. It is**

(i) lifted up with an acceleration 4.9 m/s^{2},

(ii) lowered with an acceleration 4.9 m/s^{2}.

The ratio of the tensions is

(a) 1 : 3

(b) 1 : 2

(c) 3 : 1

(d) 2:1 **(1998)**

**39. A bullet is fired from a gun. The force on the bullet is given by F= 600-2 x 10 ^{5} t where, F is in newton and t in seconds. The force on the bullet becomes zero as soon as it ‘ leaves the barrel. What is the average impulse imparted to the bullet?**

(a) 9 N-s

(b) zero

(c) 1.8 N-s

(d) 0.9 N-s

**(1998)**

**40. A mass M is placed on a very smooth wedge resting on a surface without friction. Once the mass is released, the acceleration to be given to the wedge so that M remains at rest is a where**

(a) a is applied to the left and a = gtan0

(b) a is applied to the right and a = gtan0

(c) a is applied to the left and a = gsin0

(d) a is applied to the left and a = gcos0** (1998)**

**41. A 5000 kg rocket is set for vertical firing. The exhaust speed is 800 ms**^{-1}**. To give an initial upward acceleration of 20 ms ^{-2}, the amount of gas ejected per second to supply the needed thrust will be (g = 10 ms^{-2})**

(a) 185.5 kgs

^{-1}

(b) 187.5 kgs

^{-1}

(c) 127.5 kgs

^{-1}

(d) 137.5 kgs

^{-1}

**(1998)**

**42. A force of 6 N acts on a body at rest and ofimass 1 kg. During this time, the body attains a velocity of 30 m/s. The time for which the force acts on the body is**

(a) 7 seconds

(b) 5 seconds

(c) 10 seconds

(d) 8 seconds. **(1997)**

**43. A 10 N force is applied on a body produce in it an acceleration of 1 m/s ^{2}. The mass of the body is**

(a) 15 kg

(b) 20 kg

(c) 10 kg

(d) 5 kg.

**(1996)**

**44. A force vector applied on a mass is represented as = 6 – 8 +10 and accelerates with 1 m/s ^{2}. What will be the mass of the body?**

**45. A man fires a bullet of mass 200 gm at a speed of 5 m/s. The gun is of one kg mass. By what velocity the gun rebounds backward?**

(a) 1 m/s

(b) 0.01 m/s

(c) 0.1 m/s

(d) 10 m/s. **(1996)**

**46. In a rocket, fuel bums at the rate of 1 kg/s. This fuel is ejected from the rocket with a velocity of 60 km/s. This exerts a force on the rocket equal to**

(a) 6000 N

(b) 60000 N

(c) 60 N

(d) 600 N. **(1994)**

**47. A block has been placed on a inclined plane with the slope angle 0, block slides down the plane at constant speed. The coefficient of kinetic friction is equal to**

(a) sinθ

(b) cosθ

(c) g

(d) tanθ **(1993)**

**48. A monkey is decending from the branch of a tree with constant acceleration. If the breaking strength is 75% of the weight of the monkey, the minimum acceleration with which monkey can slide down without branch is**

**49. Consider a car moving along a straight horizontal road with a speed of 72 km/h. If the coefficient of static friction between the tyres and the road is 0.5, the shortest distance in which the car can be stopped is (taking g = 10 m/s ^{2})**

(a) 30 m

(b) 40 m

(c) 72 m

(d) 20 m

**(1992)**

**50. Physical independence of force is a consequence of**

(a) third law of motion

(b) second law of motion

(c) first law of motion

(d) all of these laws** (1991)**

**51. A heavy uniform chain lies on horizontal table top. If the coefficient of friction between the chain and the table surface is 0.25, then the maximum fraction of the length of the chain that can hang over one edge of the table is**

(a) 20%

(b) 25%

(c) 35%

(d) 15%** (1991)**

**52. A particle of mass m is moving with a uniform velocity v _{1}(. It is given an impulse such that its velocity becomes v2. The impulse is equal to**

**53. A 600 kg rocket is set for a vertical fring. If the exhaust speed is 1000 ms ^{-1}, the mass of the gas ejected per second to supply the thrust needed to overcome the weight of rocket is**

**54. A body of mass 5 kg explodes at rest into three fragments with masses in the ratio 1:1:3. The fragments with equal masses fly in mutually perpendicular directions with speeds of 21 m/s. The velocity of heaviest fragment in m/s will be**

**55. Starting from rest, a body slides down a 45° inclined plane in twice the time it takes tp slide down the same distance in the absence of friction. The coefficient of friction between the body and the inclined plane is**

(a) 0.80

(b) 0.75

(c) 0.25

(d) 0.33 (1988)

### Explanations