Question

1. An object is moving with a velocity of 30 m/s in east direction on a rough horizontal surface.

(a) In which direction the friction is acting?

(b) Can friction slow down the car? Explain. What will happen eventually?

2. There is a gravitational force, which is an attractive force, in between any two objects which has masses. If we consider two books on a table, and if this so called gravitational force is there, why wouldn't they attract to each other?

Answer 1

1.

A. given object is moving is in east direction as we know that the friction force is always act opposite to the direction of motion. So friction act in the direction of west direction.

B. Friction is a force act opposite to the direction of motion. So from Newtown second law

Net force= mass* acceleration

Net force will decrease cause deacceleration so it'll reduce the motion of car.

2.

Formula of gravitational force between two bodies

Fg = Gm1m2/r2

Here G = 6.67*10^-11 Nm2/kg2

Here book mass is very less as after putting all value Fg will be very less to overcome the frictionl force between book and table . Friction force always act apposite to motion.

That's why book doesn't move towards each other on table.

Hope you will understand. Please upvote my hardwork. Thanks