Laws of Motion ...

A light string passing over a smooth light pulley connects two block of masses \(m_1\) and \(m_2\) (vertically). If the acceleration of the system is \(\frac{g}{8}\) then the ratio of masses is

The resultant of two forces 3P and 2P is R. If the first force is doubled then the resultant is also doubled. The angle between the two forces is

The resultant force of 5 N and 10 N cannot be

Which one of the following is not a force?

If a force on rocket having exhaust velocity of 300 m/s is 210 N, then rate of combustion of fuel is

A large force is acting on a body for short time. The impulse imparted is equal to change in

A lift is moving down with acceleration a. A man is on 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.

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

The spring balance inside a lift suspends an object. As the lift begins to ascent, the reading indicated by the spring balance will

Swimming is possible on account of

In an air collision between an aeroplane and a bird, the force experienced by the bird as compared to that of the aeroplane is

Which of the following group of forces could be in equilibrium?

A diwali rocket is ejecting 0.05 kg of gases per second at a velocity of 400 m/sec. The accelerating force on the rocket is 

Assertion: When a bicycle is in motion, the force of friction exerted by the ground on the two wheels is always in forward direction.

Reason: The frictional force acts only when the bodies are in contact.

(A) If both assertion and reason are true and the reason is the correct explanation of the assertion.           

(B) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(C) If assertion is true but reason is false.           

(D) If the assertion and reason both are false.

(E) If assertion is false but reason is true.

A body of mass 4 kg is accelerated upon by a constant force travels a distance of 5m in the first second and a distance of 2m in the third second. The force acting on a body is