Section A 10 Motion and Forces Progress Test

A set of vocabulary flashcards covering basic kinematics, vector and scalar definitions, and Newton's laws of motion based on the Motion and Forces Progress Test.

Displacement

An example of a vector quantity that represents a change in the position of a moving body.

Vector quantity

A quantity that has both magnitude (size or amount) and direction, such as velocity = $20\,m\,s^{-1}$ north or force = $50\,N$ to the right.

Scalar quantity

A quantity that has magnitude only (size or amount) and no direction, such as speed = $20\,m\,s^{-1}$ or distance = $100\,m$.

Average speed

The rate of change of distance, calculated as $\text{distance} / \text{time}$. In Rico's case, a $6\,km$ walk arriving in $40$ minutes resulted in $2.5\,m\,s^{-1}$ or $9.0\,km\,h^{-1}$.

Average acceleration

The rate of change of velocity, determined by the formula $a = \frac{v_2-v_1}{t}$. For example, a sports car reaching $96\,km\,h^{-1}$ in $3$ seconds has an average acceleration of $8.9\,m\,s^{-2}$.

Gravitational acceleration ($g$)

The constant acceleration of an object in free fall (ignoring air resistance), valued at $9.8\,m\,s^{-2}$ downwards.

Negative slope on a displacement – time graph

Indicates that the moving body (such as a cyclist) is moving back towards the starting point.

Newton’s first law of motion

States that an object moving at constant velocity has no resultant force acting on it, meaning forward forces (like thrust) must equal backward forces (like air resistance).

Newton’s second law of motion

A law stating that a non-zero resultant force causes an object to accelerate in the direction of the net force, represented by the formula $F_{net} = ma$.

Weight

The force exerted on an object due to gravity, calculated as $\text{Weight} = mg$. For a person of mass $50\,kg$, the weight is $490\,N$.

Deceleration

The rate at which an object slows down, calculated as negative acceleration. For a car stopping from $70\,m\,s^{-1}$ in $2.0\,s$, the deceleration is $35\,m\,s^{-2}$.

Net force ($F_{net}$) on a multi-block system

The total force causing a system of masses to move together; for a $12\,N$ force on a system of $3\,kg$, $2\,kg$, and $1\,kg$ blocks, the acceleration is $2\,m\,s^{-2}$.

Tension ($F_{tension}$)

The force transmitted through a string or tether. In a system where two masses ($4\,kg$ and $2\,kg$) are pulled upwards, the tension acting on the bottom $2\,kg$ block can be calculated as $ma$.