CBSE Class 11 Physics Laws of Motion Online Test Set E

1. 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 m s^–1 and the second part of mass 2 kg moves with 8 m s–1 speed. If the third part flies off with 4 m s^–1 speed, then its mass is

2. The engine of a car produces an acceleration of 6 ms^-2 in the car. If this car pulls another car of the same mass, then the acceleration would be

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

4. A block of mass m is placed on a surface with a vertical cross-section given by y = x³ I 6. If the coefficient of friction is 0.5, the maximum height above the ground at which the block can be placed without slipping is.

5. A block of mass 2 kg is at rest on a floor. The coefficient of static friction between block and the floor is 0.54. A horizontal force of 2.8 N is applied to the block. What should be the frictional force between the block and the floor? (take,g = 10 m/s²)

6. 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)

7. A car of mass 1000 kg negotiates a banked curve of radius 90 m on a frictionless road. If the banking angle is 45degree, the speed of the car is

8. A body is coming with a velocity of 72 kmh^-1 on a rough horizontal surface of coefficient of friction 0.5. If the acceleration due to gravity is 10 ms ^-2, find the minimum distance, it can be stopped.

9.  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)

10.  A block of mass 10 kg is in contact against the inner wall of a hollow cylindrical drum of radius 1 m.
The coefficient of friction between the block and the inner wall of the cylinder is 0.1. The minimum angular velocity needed for the cylinder to keep the block stationary when the cylinder is vertical and rotating about its axis, will be (g = 10 m/s²)

11. 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

12. 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 2m? (g is the acceleration due to gravity)

13. Question:Two particles of equal mass are connected to a rope AB of negligible mass, such that one is at end A and the other dividing the length of the rope in the ratio 1 : 2 from B. The rope is rotated about end B in a horizontal plane. Ratio of the tensions in the smaller pa1t to the other is (ignore effect of gravity)

14. Starting from rest, the time taken by a body sliding down on a rough inclined plane at45degree with the horizontal is twice the time taken to travel on a smooth plane of same inclination and same distance. Then, the coefficient of kinetic friction is

15. Question:A block of mass 2 kg rests on a horizontal surface. If a horizontal force of 5 N is applied on the block, the frictional force on it is (take,μ k = 0.4, μ s = 0.5)

16. 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 with the vertical is

17. Question:The resultant of two forces acting at an angle of I 20degree is 10 kg-wt and is perpendicular to one of the forces. That force is

18. 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

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

20. Question:A piece of wire is bent in the shape of a parabola y = kx2 (y-axis vertical) with a bead of mass m on it. The bead can slide on the wire without friction. It stays at the lowest point of the parabola when the wire is at rest. The wire is now accelerated parallel to the x-axis with a constant acceleration a. The distance of the new equilibrium position of the bead, where the bead can stays at rest with respect to the wire, from the y -axis is(