JEE Questions for Physics Laws Of Motion Quiz 13 - MCQExams.com

10,000 small balls, each weighing 1 gm, strike one square cm of area per second with a velocity 100 m/s in a normal direction and rebound with the same velocity. The value of pressure on the surface will be
  • 2 × 103 N/m2
  • 2 × 105 N/m2
  • 107 N/m2
  • 2 × 107 N/m2
A sphere is accelerated upwards by a cord whose breaking strength is four times its weight. The maximum acceleration with which the sphere can moveup without breaking the cord is
  • g
  • 3 g
  • 2 g
  • 4 g
A body of mass m collides against a wall with a velocity v and rebounds with the same speed. Its change of momentum is
  • 2 mv
  • mv
  • –mv
  • Zero
A vehicle of 100 kg is moving with a velocity of 5 m/sec.To stop it in 1/10 sec, the required force in opposite direction is
  • 5000 N
  • 500 N
  • 50 N
  • 1000 N
A boy having a mass equal to 40 kilograms is standing in an elevator. The force felt by the feet of the boy will be greatest when the elevator (g = 9.8 metres/ sec2)
  • Stands still
  • Moves downward at a constant velocity of 4 metres/sec
  • Accelerates downward with an acceleration equal to 4 metres/sec2
  • Accelerates upward with an acceleration equal to 4 metres/sec2
The ratio of the weight of a man in a stationary lift and when it is moving downward with uniform acceleration \'a\' is 3 : 2. The value of \'a\' is (g-Acceleration due to gravity of the earth)
  • 3/2 g
  • g/3
  • 2/3 g
  • g
If a person with a spring balance and a body hanging from it goes up and up in an aeroplane, then the reading of the weight of the body as indicated by the spring balance will
  • Go on increasing
  • Go on decreasing
  • First increase and then decrease
  • Remain the same
The time period of a simple pendulum measured inside a stationary lift isfound to be T. If the lift starts accelerating upwards with an acceleration g/3, the time period is

  • Physics-Laws of Motion-77532.png
  • 2)
    Physics-Laws of Motion-77533.png

  • Physics-Laws of Motion-77534.png
  • T / 3
A ball of mass 400 gm is dropped from a height of 5 m. A boy on the ground hits the ball vertically upwards with a bat with an average force of 100 newton so that it attains a vertical height of 20 m. The time for which the ball remains in contact with the bat is [g = 10 m/s2]
  • 0.12 s
  • 0.08 s
  • 0.04 s
  • 12 s
The linear momentum p of a body moving in one dimension varies with time according to the equation p = a + bt2, where a and b are positive constants. The net force acting on the body is
  • A constant
  • Proportional to t 2
  • Inversely proportional to t
  • Proportional to t
A second\'s pendulum is mounted in a rocket. Its period of oscillation decreases when the rocket
  • Comes down with uniform acceleration
  • Moves round the earth in a geostationary orbit
  • Moves up with a uniform velocity
  • Moves up with uniform acceleration
n small balls each of mass m impinge elastically each second on a surface with velocity u. The force experienced by the surface will be
  • mnu
  • 2 mnu
  • 4 mnu
  • 1/2mnu

Physics-Laws of Motion-77540.png

  • Physics-Laws of Motion-77541.png
  • 2)
    Physics-Laws of Motion-77542.png
  • 10 kg
  • 20 kg
A ball of mass 0.5 kg moving with a velocity of 2 m/s strikes a wall normally and bounces back with the same speed. If the time of contact between the ball and the wall is one millisecond, the average force exerted by the wall on the ball is
  • 2000 N
  • 1000 N
  • 5000 N
  • 125 N
The average force necessary to stop a bullet of mass20 g moving with a speed of 250 m/s, as it penetrates into the wood for a distance of 12 cm is
  • 2.2 × 103 N
  • 3.2 × 103 N
  • 4.2 × 103 N
  • 5.2 × 103 N
The average resisting force that must act on a 5 kg mass to reduce its speed from 65 cm/s to 15 cm/s in 0.2 s is
  • 12.5 N
  • 25 N
  • 50 N
  • 100 N
A person is measuring his weight by standing on a weighing machine inside a lift. When the lift is at rest, the machine shows his weight to be 55 kg. In between the floor when the lift is moving up with a constant speed of 10 km/hr, he again measures his weight, which is
  • 55 kg
  • 65 kg
  • 50 kg
  • 45 kg
An army vehicle of mass 1000 kg is moving with a velocity of 10 m/s and is acted upon by a forward force of 1000 N due to the engine and a retarding force of 500 N due to friction. What will be its velocity after 10 s
  • 5 m/s
  • 10 m/s
  • 15 m/s
  • 20 m/s
A block of mass m is placed on a smooth wedge of inclination θ. 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 (g is acceleration due to gravity) will be
  • mg cos θ
  • mg sin θ
  • mg
  • mg/cos θ
A player caught a cricket ball of mass 150 gm moving at the rate of 20 m/sec. If the catching process be completed in 0.1 sec the force of the blow exerted by the ball on the hands of player is
  • 0.3 N
  • 30 N
  • 300 N
  • 3000 N
If rope of lift breaks suddenly, the tension exerted by the surface of lift
(a = acceleration of lift)
  • mg
  • m(g + a)
  • m(g –a)
  • 0
A spring balance is attached to the ceiling of a lift. A man hangs his bag on the spring and the spring reads 49 N, when the lift is stationary. If the lift moves downward with an acceleration of 5 m/s2, the reading of the spring balance will be
  • 49 N
  • 24 N
  • 74 N
  • 15 N

Physics-Laws of Motion-77552.png
  • 5 seconds
  • 20 seconds
  • 40 seconds
  • 80 seconds
A block of mass 5 kg is moving horizontally at a speed of 1.5 m/s. A perpendicular force of 5 N acts on it for 4 sec. What will be the distance of the block from the point where the force started acting
  • 10 m
  • 8 m
  • 6 m
  • 2 m
A lift of mass 1000 kg is moving with an acceleration of 1 m/s2 in upward direction. Tension developed in the string, which is connected to the lift is (g = 9.8 m/s2)
  • 9,800 N
  • 10,000 N
  • 10,800 N
  • 11,000 N
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/s2. What would be the reading on the scale. (g = 10 m/s2)
  • 400 N
  • 800 N
  • 1200 N
  • Zero
A monkey of mass 20 kg is holding a vertical rope. The rope will not break when a mass of 25 kg 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/s2)
  • 10 m/s2
  • 25 m/s2
  • 2.5 m/s2
  • 5 m/s2
Human heart is pumping blood with constant velocity v ms–1 at the rate of M kg s–1. The force required for this is (in N)
  • M
  • Mv

  • Physics-Laws of Motion-77558.png

  • Physics-Laws of Motion-77559.png

  • Physics-Laws of Motion-77560.png
A person of mass 60 kg is inside a lift of mass 940 kg and presses the button one control panel. The lift starts moving upwards with an acceleration 1.0 m/s2. Ifg = 10 m/s2, the tension in the supporting cable is
  • 1200 N
  • 8600 N
  • 9680 N
  • 11000 N
Sand is being dropped on a conveyor belt at the rate ofM kg/s. The force necessary to keep the belt moving with a constant velocity of v m/s will be

  • Physics-Laws of Motion-77563.png
  • Zero
  • Mv newton
  • 2 Mv newton
Ten one-rupee coins are put on top of each other on a table. Each coin has a mass m. Which of the following statements is not true
  • The force on the 6th coins (counted from the bottom) due to all the coins on its top is equal to 4 mg (downwards)
  • The force on 6th coin due to 7th coin is 4 mg (downwards)
  • The reaction of the 6th coin on the 7th coin is 4 mg (upwards)
  • The total force on the 10th coin is 9 mg (downwards)
A body floats in a liquid contained in a beaker. If the whole system as shown in figure falls freely under gravity, then the upthrust on the body due to liquid is
Physics-Laws of Motion-77566.png
  • Zero
  • Equal to the weight of liquid displaced
  • Equal to the weight of the body in air
  • None of the above
Newton\'s third law of motion leads to the law of conservation of
  • Angular momentum
  • Energy
  • Mass
  • Momentum
A bird weighs 2 kg and is inside a closed cage of 1 kg. If it starts flying, then what is the weight of the bird and cage assembly
  • 1.5 kg
  • 2.5 kg
  • 3 kg
  • 4 kg
A man is standing on a balance and his weight is measured. If he takes a step in the left side, then weight
  • Will decrease
  • Will increase
  • Remains same
  • First decreases then increases
A man is standing at a spring platform. Reading of spring balance is 60 kg wt. If man jumps outside platform, then reading of spring balance
  • First increases then decreases to zero
  • Decreases
  • Increases
  • Remains same
A bird is sitting in a large closed cage which is placed on a spring balance. It records a weight of 25 N. The bird (mass m = 0.5 kg) flies upward in the cage with an acceleration of 2 m/s2. The spring balance will now record a weight of
  • 24 N
  • 25 N
  • 26 N
  • 27 N
A book is lying on the table. What is the angle between the action of the book on the table and the reaction of the table on the book
  • 0°
  • 30°
  • 45°
  • 180°
In an air collision between an aeroplane and a bird, the force experienced by the bird as compared to that of the aeroplane is
  • Very high
  • Equal
  • Less
  • Zero
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 kgsecond part moving with a velocity of 8 ms–1. If the third part flies off with a velocity of 4 ms–1, its mass would be
  • 5 kg
  • 7 kg
  • 17 kg
  • 3 kg
A wagon weighing 1000 kg is moving with a velocity 50 km/h on smooth horizontal rails. A mass of 250 kg is dropped into it. The velocity with which if moves now is
  • 2.5 km/hour
  • 20 km/hour
  • 40 km/hour
  • 50 km/hour
If a force of 250 N act on body, the momentum acquired is 125 kg-m/s. What is the period for which force acts on the body
  • 0.5 sec
  • 0.2 sec
  • 0.4 sec
  • 0.25 sec
A 100 g iron ball having velocity 10 m/s collides with a wall at an angle 30° and rebounds with the same angle. If the period of contact between the ball and wall is 0.1 second, then the force experienced by the wall is
  • 10 N
  • 100 N
  • 1.0 N
  • 0.1 N
A ball of mass 150 g starts moving with an acceleration of 20 m/s2. When hit by a force, which acts on it for 0.1 sec the impulsive force is
  • 0.5 N-s
  • 0.1 N-s
  • 0.3 N-s
  • 1.2 N-s
A body, whose momentum is constant, must have constant
  • Force
  • Velocity
  • Acceleration
  • All of these
The motion of a rocket is based on the principle of conservation of
  • Mass
  • Kinetic energy
  • Linear momentum
  • Angular momentum
An aircraft is moving with a velocity of 300 ms–1. If all the forces acting on it are balanced, then
  • It still moves with the same velocity
  • It will be just floating at the same point in space
  • It will fall down instantaneously
  • It will lose its velocity gradually
  • It will explode
Rocket engines lift a rocket from the earth surface because hot gas with high velocity
  • Push against the earth
  • Push against the air
  • React against the rocket and push it up
  • Heat up the air which lifts the rocket
A man fires a bullet of mass 200 g at a speed of 5 m/s. The gun is of 1 kg mass. By what velocity the gun rebounds backwards
  • 0.1 m/s
  • 10 m/s
  • 1 m/s
  • 0.01 m/s
A force of 50 dynes is acted on a body of mass 5 g which is at rest for an interval of 3 seconds, then impulse is
  • 0.15 ×10–3 Ns
  • 0.98 ×10–3 Ns
  • 1.5 ×10–3 Ns
  • 2.5 ×10–3 Ns
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