✓✗A 40 kg slab rests on a frictionless floor. A 10 kg block rests on top of it. The coefficients of static and kinetic friction between block and slab are 0.6 and 0.4. A horizontal force of 100 N acts on the block. The acceleration of the slab is (g = 10 m s⁻²)

✓✗A person holding a rifle (mass of person and rifle together is 100 kg) stands on a smooth surface and fires 10 shots horizontally in 5 s. Each bullet has a mass of 10 g and a muzzle velocity of 800 m s⁻¹. The final velocity acquired by the person and the average force exerted on the person are

✓✗For a given pair of surfaces, which is the correct order?

✓✗A block takes time t to slide down a smooth incline and time 3t to slide down the same incline when it is rough. If the incline angle is 45°, the coefficient of kinetic friction is

✓✗Starting from rest, a body slides down a 45° inclined plane in twice the time it takes to slide down the same distance in the absence of friction. The coefficient of friction between the body and the plane is

✓✗A stone of mass 0.25 kg tied to a string is whirled in a horizontal circle of radius 1.5 m with a speed of 40 rev/min. The tension in the string is (NCERT)

✓✗A bob is whirled in a horizontal plane by means of a string with an initial angular speed of ω rpm. The tension in the string is T. If the angular speed becomes 2ω while keeping the same radius, the tension in the string becomes

✓✗A block of mass 2 kg on a rough horizontal surface (μ = 0.25) is pulled by a force of 10 N at 37° above the horizontal. Its acceleration is (g = 10 m s⁻², sin37° = 0.6)

✓✗A body at rest breaks into three pieces. Two pieces of equal mass m fly off at right angles with speed v each. If the third piece has mass 2m, its speed is

✓✗A picture of weight W hangs from a nail by a string whose two halves make an angle of 120° with each other. The tension in the string is

✓✗A mass M is placed on a very smooth wedge of inclination θ resting on a frictionless surface, as shown.

The acceleration a to be given to the wedge so that M remains at rest relative to the wedge is

✓✗When we walk on the ground, the force that pushes us forward is

✓✗A 1 kg ball tied to a 1 m string is whirled in a vertical circle. At the lowest point its speed is 6 m s⁻¹. The tension at the lowest point is (g = 10 m s⁻²)

✓✗Two bodies of masses 1 kg and 4 kg have equal kinetic energies. The ratio of their momenta is

✓✗The law of conservation of linear momentum holds when