Physics 1 Marks Question

When the string breaks, the stone will move in the direction of the velocity at that instant. According to the first law of motion, the direction of velocity vector is tangential to the path of the stone at that instant. Hence, the stone will fly off tangentially from the instant the string breaks.

Force is being applied to overcome the force of friction. But as velocity of the car is constant, its acceleration, a = 0. Hence net force on the car F = ma = 0.

As the cork is floating on water, its weight is balanced by the up thrust due to water. Therefore, the net force on the cork is 0.

As the high speed electron in space is far away from all gravitating objects and free of electric and magnetic fields, the net force on electron is 0.

As the rain drop is filling with a constant speed, its acceleration, a = 0. Hence net force F = ma = 0.

As the kite is held stationery, in accordance with the first law of motion, the net force on the kite is 0.

Mass varies at every moment.

It is the reaction due to the surface on which the body moves. It acts perpendicular to the surface of contact.

Mass of a pebble = 0.05kg Since a pebble is thrown vertically upward, then it is accelerated downwards under the influence of a gravity pull. Net force on the pebble = mg = 0.05 × 10 = 0.5N vertically downward.

As the applied force increases, the static friction also increases and becomes equal to the applied force to make the object stationary. That is why static friction is called a self-adjusting force.

Sliding friction.

Friction, a tangential force provides the necessary torque to roll the body. This has to act opposite in the direction of motion to bring necessary motion.

Since earth rotates on its own axis and also revolves around the sun, there will be acceleration associated. So earth cannot be taken as inertial frame of reference.

The maximum height is reduced.

Any change in area, leads to only variation in the pressure experienced, but the force to be balanced remains the same.

Maximum static friction acting on body is known as limiting friction.

Remains constant.

Curved roads are generally banked so as to help in providing centripetal force needed to balance the centrifugal force, arising due to circular motion on the curved road.

Momentum transferred depends on mass and time in which it is brought to rest.

The electrostatic force of attraction between the nucleus and the electrons.

1. Electrostatic force.
2. Gravitational force.

They always act on the two bodies in contact and not on the same body.

It is dangerous because:When the passengers are standing in the bus, the centre of gravity of the system is raised and as such the whole system is in an unstable equilibrium.
When the running bus suddenly stops due to inertia of motion, the passengers fall forward on each other and this will cause a stampede.

To make use of a component of normal reaction to negotiate the curve.

The stone will move along the tangent at the point of breaking.

No, centripetal force always acts towards the centre.

Due to inertia.

If on applying same force on the bodies, same acceleration is produced, then their inertial masses are same.

It is easier to roll a barrel because at the time of rolling we require to apply a force in order to overcome rolling friction and value of rolling friction is much less than sliding friction.

The statement is correct. It is in accordance with Newton's second law of motion.

Friction depends on the hardness and smoothness of the surfaces in contact. So proper inflation is required.

Momentum of a body is defined as the product of its mass and the velocity with which it is moving Momentum = Mass × Velocity Momentum of a body depends upon it mass and the velocity.

Impulse

1kg wt. = 9.8 newton.

Zero.