Force, Mass, and Motion Lecture Notes

This set of vocabulary flashcards covers fundamental physics concepts including Newton's laws, force types, mechanical equilibrium, and the relationship between mass, weight, and gravity.

Force

A push or pull that is a vector quantity, containing both magnitude and direction, and is measured in Newtons ($N$).

Weight

The downward pull of gravity on a body that depends on where the object is in the universe.

Tension

The force present in a stretched rope or string.

Friction

A force that stops objects and acts as the resistance which must be overcome when one surface moves over another; it always acts in the opposite direction to movement.

Resultant Force

The single force formed when at least two forces acting through the same point are combined.

Newton’s second law in motion

The relationship linking force, mass, and acceleration together, expressed by the formula $F = ma$.

Mass

The amount of matter an object contains, measured in $kg$, which remains unchanged regardless of location in the universe.

Acceleration

The change of speed with time, measured in $m/s^2$ or $ms^{-2}$, and calculated as $a = \frac{F}{m}$.

Gravity

The pull of a large body on a much smaller body.

Weight (Formula)

The pull of a body caused by gravity, determined by the formula $W = mg$, where $W$ is weight, $m$ is mass, and $g$ is acceleration due to gravity.

Acceleration due to gravity on Earth ($g$)

The gravitational pull on objects which causes an acceleration of $9.81s^2$ (or $10\,m/s^2$ or $10\,N/kg$).

Acceleration due to gravity on the Moon ($g$)

The gravitational pull which causes an acceleration of $1.3\,m/s^2$ or $1.3\,N/kg$, resulting in a mass of $100\,kg$ weighing only $130\,N$.

Centre of gravity

The point at which the whole weight of a body is acting; it is equivalent to the centre of mass.

Stable equilibrium

A condition in which a body returns to its original position after being given a small displacement; this is more likely with a lower centre of gravity.

Neutral equilibrium

A state where a body has no tendency to return to its original position or move further away when given a displacement, because the vertical from the centre of gravity always passes through the point of contact with the surface.

Unstable equilibrium

A condition in which an object will move further away from its original position when displaced.

Newton’s first law of motion

States that if an object has no force on it, it will remain stationary if it was still, or continue moving at a steady speed in a straight line if it was moving.

Physical Cause of Friction

Caused by the interlocking of 'hills and valleys' between two surfaces that appear smooth but are in fact rough, resulting in heat and the surfaces wearing away.