Q.1
A body under the action of a force F=6 i - 8j + 10k.acquires an acceleration of 1 m/s2 The mass of this body must be [ CBSE-PMT 2009]
  • a) 10kg
  • b) 20 kg
  • c) 10√2kg
  • d)2√10kg
Q.2
A light string passing over a smooth light pulley connects two blocks of masses m1 and m2 ( vertically) if the acceleration of system is g/8, then the ratio of masses is ... [ CBSE-PMT 2010]
  • a)8:1
  • b) 9:7
  • c)4:3
  • d)5:3
Q.3
A 60kg man stands on a spring scale in the lift. At same instant he finds, scale reading has changed from 60 kg to 50kg for a while and comes back to the original mark. What should we conclude? [ AFMC 2007]
  • a) The lift was in constant motion upwards
  • b) The lift was in constant motion downwards
  • c)The lift while in constant motion upwards is stopped suddenly
  • d)The lift while in constant motion downwards, is suddenly stopped
Q.4
In Newton's second law F =m a , a is the acceleration of the mass 'm' with respect to [ AFMC 2011]
  • a) Any observer
  • b) Any inertial observer
  • c)an observer at rest only
  • d)an observer moving with uniform speed only
Q.5
A motor cycle is going on an over bridge of radius R. The driver maintains a constant speed. As the motor cycle is ascending on the over bridge the normal force on it... [ AFMC 2006]
  • a) increases
  • b) decreases
  • c) remains the same
  • d) fluctuates erratically
Q.6
The limiting friction is ... [ AFMC 2007]
  • a)always greater than the dynamic friction
  • b) always less than the dynamic friction
  • c)equal to the dynamic friction
  • d)sometimes greater and sometimes less than the dynamic friction
Q.7
A person swimming in a fresh water pool obeys [ AFMC 2003]
  • a) Newton's second law
  • b) Gravitational law
  • c)Newton's third law
  • d)Newton's first law
Q.8
When a car moves on a road with uniform speed of 30km/hr, then the resultant force on the car is ... [ AFMC 2004]
  • a) The driving force, drives the car in the direction of propagation of car
  • b) The resistive force acts opposite to the direction of propagating of car
  • c)zero
  • d)none of these
Q.9
A cyclist moving with a speed of 4.9 m/s on a level road can take a sharp circular turn of radius 4m, then coefficient of friction between the cycle tyres and road is ... [ AFMC 2002]
  • a) 0.71
  • b) 0.61
  • c) 0.31
  • d) 0.81
Q.10
A spring of length L of uniform cross-section is spread on a smooth plane. One of its end is pulled by a force F as shown in the figure. The Tension in the spring at a distance 'l' from this end is .. [ AFMC 2010]
ch-4_que_no-37_img_no1.png
  • a)
    ch-4_qn-37choice_img_no1.png
  • b)
    ch-4_qn-37choice_img_no2.png
  • c)
    ch-4_qn-37choice_img_no3.png
  • d)
    ch-4_qn-37choice_img_no4.png
Q.11
A bullet of mass m is fired from a gun of mass M. The recoiling gun compresses a spring of force constant k by a distance d. Then the velocity of bullet is .. [ AFMC..2011]
  • a)
    ch-4_qn-38choice_img_no1.png
  • b)
    ch-4_qn-38choice_img_no2.png
  • c)
    ch-4_qn-38choice_img_no3.png
  • d)
    ch-4_qn-38choice_img_no4.png
Q.12
Which of the following is self adjusting force? [ AFMC 2009]
  • a) kinetic friction
  • b) static friction
  • c) Nuclear force
  • d) None of these
Q.13
A body of mass 4.975kg is lying on the frictionless floor. A mass of 25gm moving with 400m/s strikes the mass and gets embedded in it. The velocity of the body combined after collision is ... [ AFMC 2006]
  • a) 2 m/s
  • b) 4 m/s
  • c) 1 m/s
  • d) none of these..
Q.14
The rocket engine lift a rocket from the earth, because hot gases: [ AIIMS 1998]
  • a)push it against the air with very high velocity
  • b) push it against the earth with very high velocity
  • c)heat up the air which lifts the rocket with very high velocity
  • d)react against rocket and push it up with very high velocity
Q.15
A man of mass 60kg records his weight on a weighing machine placed inside a lift. the ratio of weight of man recorded when lift ascending up with uniform speed of 2m/s to when it is descending down with uniform speed of 4m/s [ AIIMS 2007}
  • a) 0.5
  • b) 1.0
  • c)2.0
  • d)none of these
Q.16
When a horse pulls a wagon, the force that causes the horse to move forward in the force [ AIIMS 2010]
  • a) the ground exerts on it
  • b) it exerts on the ground
  • c)the wagon exerts on it
  • d)it exerts on the wagon
Q.17
A person standing in an elevator. in which situation he finds his weight less? [ AIIMS 2005]
  • a) When the elevator moves upward with constant acceleration.
  • b) When the elevator moves downward with constant acceleration
  • c) When the elevator moves upward with uniform velocity
  • d) When the elevator moves downward with uniform velocity
Q.18
A 1kg particle strikes a wall with a velocity 1m/s at an angle 30° and reflects at the same wall in 0.1 second then the force will be: [ AIIMS 1999]
  • a)30√3 N
  • b) 0
  • c)40√3 N
  • d)10√3 N
Q.19
A 150 g tennis ball coming at a speed of 40 m/s is hit straight back by a bat to a speed of 60 m/s. the magnitude of the average force F on the ball, when it is in contact for 5 ms is ... [ AIIMS 2011]
  • a) 2500 N
  • b) 3000 N
  • c)3500 N
  • d)4000 N
Q.20
A gardener holds a hosepipe through which water is gushing out at a rate of 4 kg/s with speed 2m/s. The moment the speed of water is increased to 3m/s, the gardener will experience a jerk of ... [ AIIMS 2011]
  • a)4 N in backward direction
  • b)8 N in forward direction
  • c)8 N in backward direction
  • d)4 N in forward direction
Q.21
A bomb of mass 3.0 kg explodes in air into two pieces of masses 2.0kg and 1.0kg. the smallest mass goes at a speed of 80 m/s. the total energy imparted to the two fragments is.. [ AIIMS 2004]
  • a) 1.07 kJ
  • b) 2.14 kJ
  • c) 2.4 kJ
  • d) 4.8 kJ
Q.22
If the force on rocket, moving with a velocity 500 m/s is 400N, then the rate of combustion of the fuel will be.. [ AIIMS 1997]
  • a)0.8 kg/sec
  • b) 10.8 kg/sec
  • c)8 kg/sec
  • d)1.6 kg/sec
Q.23
The velocity of bullet is reduced from 200m/s to 100 m/s while traveling through a wooden block of thickness 10cm. Assuming it is to be uniform, the retardation will be.. [ AIIMS 2001]
  • a) 15×104 m/ s2
  • b) 10×104 m/ s2
  • c)12×104 m/ s2
  • d)14.5 m/ s2
Q.24
An 80 kg person is parachuting and is experiencing a downward acceleration of 2.8 m/s2 . The mass of the parachute is 5kg. The upward force on the open parachute is .. ( g=9.8 m/s2)
  • a)595 N
  • b) 675 N
  • c)456 N
  • d)925 N
Q.25
A parachutist after bailing outfalls 50 m without friction. When parachute opens. If decelerates at 2m/sHe reaches the ground with a speed of 3m/s. At what height, did he bail out? take g=9.8 m/s2 [ AIIMS 2009]
  • a) 182 m
  • b) 91 m
  • c) 111 m
  • d) 293 m
Q.26
A lift is moving down with acceleration a. A man in the lift drops a ball inside the lift. The acceleration of the ball as observed by the man in the lift and a man standing stationary on the ground are respectively.. [ AIEEE2002]
  • a)g, g
  • b) g-a, g-a
  • c)g-a, g
  • d)a, g
Q.27
A spring balance is attached to the ceiling of lift. A man hangs his bag on the spring and the spring reads 49N, when the lift is stationary. If the lift moves downwards with an acceleration of 5 m/s2, the reading of the spring balance will be [ AIEEE-2003]
  • a) 24N
  • b) 74N
  • c)15N
  • d)49N
Q.28
A light string passes over a smooth light pulley connects two blocks of masses m1 and m2 ( vertically). If the acceleration of the system is g/8, then the ratio of the masses is [ AIEEE 2002]
  • a) 8:1
  • b) 9:7
  • c)4:3
  • d)5:3
Q.29
One end of a mass less rope, which passes over a mass less and frictionless pulley P is tied to a hook C while the other end is free. Maximum tension that the rope can bear is 840N. With what value of maximum safe acceleration (in m/s2) can a man of 60 kg climb on the rope [ AIEEE 2002]
ch-4_que_no-56_img_no1.png
  • a) 16
  • b) 6
  • c) 4
  • d) 8
Q.30
Three identical blocks of mass m=2 kg are drawn by a force F=10.2N on a friction less surface, then what is the tension (in N) in the sting between the blocks B and C? [ AIEEE 2002]
ch-4_que_no-57_img_no1.png
  • a)9.2
  • b) 3.4
  • c)4
  • d)9.8
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