If the tension in the cable supporting an elevator is equal to the weight of the elevator, the elevator may _______.

A block of mass M is pulled along a horizontal frictionless surface by a rope of mass m. Force P is applied at one end of the rope. The force which the rope exerts on the block is: _______.

A force of 200 N is required to push a car of mass 500 kg slowly at constant speed on a level road. If a force of 500 N is applied, the acceleration of the car (in m S^-2) will be_______.

Water is poured from a height of 10m into an empty barrel at the rate of 1 litre per second. If the weight of the barrel is 10 kg, the weight indicated at time t = 60 s will be _______.

The physical quantity which is equal to the change in momentum of a body is known as _______.

Bodies of larger mass need greater initial effort to put them in motion. why ?

A force of 1 N acts on a body of mass 1 g. Calculate the acceleration produced in the body.

Calculate the force acting on a body which changes the momentum of the body at the rate of 1 kg m/s².

The distance travelled by a moving body is directly proportional to time. Is any external force acting on it ?

A force of 36 dyne is inclined to the horizontal at an angle of 60\(^0\) . Find the acceleration in a mass of 18 g that moves in a horizontal diraction.

A passenger of mass 72.2 kg is riding in an elevator while standing on a platform scale. What does the scale read when the elevator cab is 
(i) descending with constant velocity
(ii) ascending with constant acceleration, 3.5 m/s²?

A person of mass 50 kg stands on a weighing scale on a lift. If the lift is descending with a downwards acceleration of 9 m/s² , what would be the reading of the weighing scale ?
When a lift descends with a downward acceleration 8, V the apparent weight of a body of mass m is given by w' = R = m (g - a)

A person driving a car suddenly applies the brakes on seeing a child on the road ahead. If he is not wearing seat belt, he falls forward and hits his head against the steering wheel. Why ?

What is the angle of friction between two surfaces in contact, if coefficient of friction is \(\sqrt{3}?\)

What is the angle between frictional force and instantaneous velocity of the body moving over a rough surface?

A body of mass 5 kg is acted upon by two perpenticular forces 8 N and 6 N . Find the magnitude and direction of the acceleration.

A helicopter of mass 1000 kg reises with a vertical acceleration of 15m /s². The crew and the passengers weigh 300 kg. Give the magnitude and direction of the
(i) force on floor by the crew and passengers.
(ii) action of the rotor of the helicopter on the surrounding air
(iii) force on the helicopter due to the surrounding air, take g = 10 m/s².

A body of mass 500 g tied to a string of length 1 m is revolved in the vertical circle with a constant speed. Find the minimum speed at which there will not be any slack on the string. Take g = 10 ms^-2·

A 20 kg box is gently placed on a rough inclined plane of inclination 30° with horizontal. The coefficient of sliding friction between the box and the plane is 0.4. Find the acceleration of the box down the incline.

An artificial satellite of mass 2500 kg is orbiting around the earth with a speed of 4 kms^-1 at a distance of 10^-4 from the earth. Calculate the centripetal force action on it.

A male astronaut 82 kg and a female astronaut 64 kg are floating side by side in space.
(i) Determine the acceleration of each astronaut if the woman pushes on the man with a force of 16 N (left)
(ii) How will your answer change if the man pushes with 16 N (Right) on the woman instead?
(iii) How will your answer change if they both reach out and push on each other's shoulders with a force of 16 N?