PHY C2: Types of Forces

What are the four fundamental forces in nature?

Gravitational force, Electromagnetic force, Strong nuclear force (not in syllabus), Weak (nuclear) force.

From what are other known forces derived?

The four fundamental forces; most contact forces (pushes, pulls, normal force, friction) are due to the electromagnetic force.

What forces will be covered in H2 Physics Syllabus related to fields?

Gravitational force on mass in gravitational field, electric force on charge in electric field, magnetic force on current-carrying conductor in magnetic field.

What is Weight (W)?

The force experienced by a body of mass m in a gravitational field. W = mg.

What is Centre of Gravity (C.G.)? (Definition)

The point at which the weight of the body (or the resultant of the distributed gravitational attraction on the body) appears to act. This force acts vertically downwards towards Earth's centre.

What is Normal Contact Force (N)?

The force exerted on a body when it is in contact with a surface.

What is the direction of Normal Contact Force?

Always perpendicular to the contact surface and points away from that surface.

What is Buoyant Force (Upthrust) (U)? [Not in H1 syllabus]

The vertical upward force exerted on a body by a fluid when it is fully or partially submerged in the fluid due to difference in fluid pressure.

What is Buoyant Force equal to?

The magnitude of the weight (W) of the fluid displaced by a submerged or floating object, and opposite in direction.

What is the consequence if upthrust is greater than the object's weight?

The object will accelerate up (float).

What is the consequence if upthrust is less than the object's weight?

The object will accelerate downwards (sink).

What is Frictional Force (Friction)?

The force that acts to oppose the relative motion or tendency of relative motion between two surfaces in contact.

What is the direction of Frictional Force?

Always parallel to the two surfaces in contact.

What are some benefits of Friction?

Enables walking, holding objects securely, allows wheels to rotate without slipping.

What are some disadvantages of Friction?

Causes wear and tear in mechanical systems, produces excess heat, may cause damage.

What are examples of Friction?

Static friction, Sliding/kinetic friction, Rolling friction, Viscous forces (fluid friction).

What is Viscous Force?

A force that arises when an object moves through a fluid, imparting momentum to fluid molecules and causing itself to slow down (e.g., air resistance).

What factors does Viscous Force depend on? (Factors affecting Viscous Force)

The shape of the body, the speed of the body, and the viscosity of the fluid.

What is Tension?

The magnitude of the pulling force (F) exerted on an object (e.g., bar, rod, wire) when pulled at its ends. Denoted by T.

What is Compression?

The state of an object (e.g., rigid rod) when it is pushed on both ends.