3.2- Force in action

What is meant by terminal velocity?

When the forces acting on the falling object become balanced so the resultant force is 0, acceleration becomes 0, moving at max velocity.

What is the principle of moments?

For an object in equilibrium the sum of the clockwise moments is equal to the sum of the anticlockwise moments.

What is a moment?

A turning force.

Force x perpendicular distance (from action force)

What is meant by a couple?

A pair of equal and opposite forces, equal magnitude, opposite direction, applied to a body parallel to each other but not along same line.

If you have a uniform object, where would its centre of mass be?

At the geometric centre of object.

What is meant by density?

Mass per unit volume of a substance.

What is meant by pressure?

The pressure is the normal force exerted on a surface per unit area. Measured in Pascals (Pa), where 1 Pa = 1Nm^-2

What is the force that an object submerged in a fluid experiences?

It experiences an upward force called upthrust.

Pressure at bottom surface of object is greater than at it's top surface.

State Archimedes principle

The upthrust exerted on a body immersed in fluid, whether partially or fully submerged, is equal the weight of the fluid that the body displaces.

An object will sink if the upthrust is smaller than the weight.

For a floating object, its weight is equal to the upthrust.