Three equal weights of 3 kg each are hanging on a string pas

Subject

Physics

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

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

  

  • 13.5 J

  • 10 J

  • 15 J

  • 20 J


2.

A body is moved along a straight line by a machine delivering constant power. The distance travelled by the body in  time t is proportional to

  • t1/2

  • t

  • t3/2

  • t2


3.

A body is projected horizontally with a velocity 42  m/sec. The velocity of the body after 0.7 seconds will be nearly ( Take g = 10 m/sec2 )

  • 10 m/sec

  • 9 m/sec

  • 19 m/sec

  • 11 m/sec


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4.

Three equal weights of 3 kg each are hanging on a string passing over a frictionless pulley as shown in figure. The tension in the string between masses  II  and  III  will be ( Take  g = 10 m/sec2 )

 

  • 5 N

  • 6 N

  • 10 N

  • 20 N


D.

20 N

Three equal weights of 3 kg each are hanging on a string passing over a pulley as shown in figure

 

If  α  is the common acceleration.

      T - 3g = 3α   (for mass I)

     3g + T1 - T = 3α ( for mass II )

     3g - T1 = 3α ( for mass III )

Adding above three equations

      3g = 9α 

        α = g3

  T1 = 3g - 3 α

       = 3g - g

  T1 = 2g

  T1 = 20N


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5.

A  ball  is  bouncing  down  a  flight of stairs. The  coefficient  of  restitution  is  e. The  height of  each  step  is  d  and  the  ball  descends one  step  each  bounce. After  each  bounce  it   rebounds  to  a  height h  above  the  next  lower  step. The  height  is  large  enough  compared  with  the  width of  step  so  that  the  impacts  are  effectively  head-on.  Find the  relationship  between  h  and  d.

  • h = d1 - e2

  • h = d1 + e2

  • h = d1 + e

  • h = d1 - e2


6.

A  wire  of  length  l and  mass  m  is  bent  in the  form of  a  semicircle. The   gravitational  field  intensity  at the  centre  of  semicircle  is

   

  • G mπ l along x - axis

  • G mπ l along y-axis

  • 2π G ml2 along y-axis

  • 2 π G ml2 along x-axis


7.

Assertion:  Generally  the  path  of  a  projectile from  the  earth  is  parabolic  but  it  is elliptical  for  projectiles  going  to  a very  great  height.

Reason:  Up to ordinary height the  projectile  moves under  a  uniform  gravitational  force, but  for  great  heights,  projectile  moves  under a  variable force.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


8.

Assertion:  Angular  speed  of  a  planet  around  the  sun  increases,  when  it  is  closer to the sun.

Reason: Total angular momentum of the system remains constant.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


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9.

Assertion:  Impulsive  force  is  large  and  acts  for a short time.

Reason: Finite  change  in  momentum  should  be  produced  by  the  force.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


10.

Which of the following graph depicts spring constant k versus length l of the spring correctly?


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