Laws of Motion

A block of mass m is placed on a smooth wedge of inclination . 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)

1. mg
2. mg
3. mg
4. mg/

The coefficient of static friction, s, 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. (g = 10 m/s2) [figure]

1. 2.0 kg
2. 4.0 kg
3. 0.2 kg
4. 0.4 kg

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)

1. zero
2. 400 N
3. 800 N
4. 1200 N

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/s2)

1. 5 m/s2
2. 10 m/s2
3. 25 m/s2
4. 2.5 m/s2

A stationary particle explodes into two particles of masses m1 and m2 which move in opposite directions with velocities v1 and v2. The ratio of their kinetic energies E1/E2 is :

1. m2/m1
2. m1/m2
3. 1
4. m1v2/m2v1

An object of mass 3 kg is at rest. Now a force of F = 6t2 i + 4t j is applied on the object then velocity of object at t = 3 sec. is

1. 18 i + 3 j
2. 18 i + 6 j
3. 3 i + 18 j
4. 18 i + 4 j

A lift of mass 1000 kg which is moving with acceleration of 1 m/s2 in upward direction, then the tension developed in string which is connected to lift is

1. 9800 N
2. 10,800 N
3. 11,000 N
4. 10,000 N

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

1. 10 m/s2
2. 5 m/s2
3. 15 m/s2
4. 0.5 m/s2

On the horizontal surface of a truck a block of mass 1 kg is placed ( = 0.6) and the truck is moving with acceleration 5 m/s2, then the frictional force on the block will be

1. 5 N
2. 6 N
3. 5.88 N
4. 8 N

A cricketer catches a ball of mass 150 g in 0.1 s moving with speed 20 m/s, then he experiences a force of

1. 300 N
2. 30 N
3. 3 N
4. 0.3 N