Physics: Forces and Friction Practice Flashcards

A set of vocabulary flashcards covering basic force types, including gravity, normal force, friction, and tension, based on physics lecture notes.

Gravitational Force (Weight)

A force of attraction that earth exerts on an object and is always acting downwards towards the centre of the Earth, calculated as $F_g = mg$.

Mass ($m$)

A quantity that is always constant and is directly proportional to the net force.

Acceleration due to gravity ($g$)

The constant acceleration towards the Earth's center, valued at $9.8\,m/s^2$.

Normal Force ($F_N$ or $N$)

A contact force exerted by a surface on an object that acts at a $90^{\circ}$ angle (perpendicular) to the surface.

Normal Force on a slope

The perpendicular force exerted by a surface on an object on an incline, calculated as $N = mg\cos(\theta)$, where the angle of the slope affects the magnitude.

Frictional force ($F_f$)

A force that opposes the motion of an object and acts parallel to the surface.

Static frictional force ($f_s$)

A force that opposes motion and acts parallel to the surface when an object is at rest.

Kinetic frictional force ($f_k$)

A force that opposes motion and acts parallel to the surface of a moving object.

Maximum static frictional force ($f_{s,max}$)

The force that must be overcome for an object to start moving, expressed as $f_{s,max} = \mu_s N$.

Coefficient of friction ($\mu$)

The ratio between frictional force and normal force ($\mu = \frac{F}{N}$) which has no units and depends on the materials of the two surfaces in contact.

Applied force

A force that a person or another object exerts on an object.

Tension Force ($T$ or $F_T$)

A force experienced by a rope, string, or cable that acts in the direction of the rope and complies with Newton's Third Law.