IB Physics A2 Notes

Types of forces

In Topic A.1, the force of gravity and fluid resistance were discussed. In Topic A.2, you need to know more detail about forces and how they impact the motion of objects, including their momentum. Forces are actions that cause the deformation or change in velocity (acceleration) of an object, measured in Newtons (N). Forces act on one object at a time with magnitude and direction and may be exerted by other objects.

The main types of forces encountered are:

1. Gravitational (F_g) – the attractive force exerted by an object’s mass on another object, referred to as the affected object’s weight (W).
2. Electric (F_e) – the force between two electrically charged objects.
3. Magnetic (F_m) – the force between two magnetic objects.
4. Normal (F_N) – the force a surface perpendicularly exerts on an object due to its weight.
5. Friction (F_f) – the force a surface parallelly exerts to counteract another surface’s motion.
6. Elastic restoring force (F_H) - the force a spring exerts in both directions on another object when it is squished or stretched.
7. Tension (T) – the force a rope or cable exerts in both directions on another object when it is stretched.
8. Viscous drag force (F_d) - the force opposing the motion of a small sphere through a fluid.
9. Buoyancy (F_b) - the force on a body due to its displacement of fluid.