Physics · Laws Of Motion · NEET
It can be either. A force is any push or pull that one object applies on another. When you kick a ball you push it; when a magnet lifts a nail it pulls it. Both are forces. Force is a vector, so it always has a size (in newtons) and a direction.
A contact force acts only when two bodies touch, like friction, tension in a string, the normal reaction from a table, or a push from your hand. A non-contact force acts across empty space with no touching, like gravity, the electric force between charges, and the magnetic force. For NEET, remember: gravity, electric, and magnetic forces are the three main non-contact (field) forces.
No. A force tries to change motion, but it may not succeed if it is balanced. If you push a heavy wall, it does not move because friction and the wall's reaction balance your push. Motion changes only when there is a net (unbalanced) force. This is the idea behind Newton's first law.
A single force can do five things: (1) start a body at rest moving, (2) stop a moving body, (3) increase its speed, (4) decrease its speed, and (5) change its direction. A force can also change the shape or size of a body, for example stretching a spring or squeezing a ball.
No. Gravity acts even when nothing is touching, so it is a non-contact force. A stone dropped from a roof speeds up because Earth pulls it down through empty space. This pull acts at a distance, which is why gravity, electric, and magnetic forces are grouped as field forces.
Because the result of a force depends on its direction, not just its size. A 10 N push to the right and a 10 N push to the left give opposite results. So force needs both magnitude and direction, which makes it a vector. This is why forces are added using vector rules, not simple arithmetic.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
The SI unit of force is the newton (N). One newton is the force that gives a mass of 1 kg an acceleration of 1 m/s^2, so 1 N = 1 kg m/s^2.
Gravitational force, electromagnetic force, the strong nuclear force, and the weak nuclear force. All everyday forces like friction, tension, and normal reaction are large-scale results of the electromagnetic force between atoms.
Friction is a contact force. It acts only where two surfaces touch and always opposes relative sliding between them.
Yes. Many forces can act together. Their combined effect is found by vector addition, and only the net force decides how the motion changes.
Every problem in Laws of Motion, from friction and inclined planes to circular motion, starts by listing the forces on a body. Knowing which forces are contact or non-contact and how to draw them correctly is the base for free body diagrams and F = ma.
