Assertion (A) : Friction enables us to walk on the floor.

Reason (R) : A smooth surface exerts larger force of friction than a rough surface.

Assertion (A) : Gravitational force is a noncontact force.

Reason (R) : Gravitational force exists everywhere in the universe.

Assertion (A) : When the resultant of all the forces acting on a body is zero, the forces are said to be unbalanced.

Reason (R) : The unbalanced forces can change direction of motion.

Assertion (A) : When a force is applied on a moving object in the direction of motion, its speed increases.

Reason (R) : When a force is applied on a soft object, it changes the size and shape of the object.

Assertion (A) : A force has both the magnitude and direction.

Reason (R) : Atmospheric pressure increases with altitude.