10.2 Science Unit 2 - Motion

SI units

The seven fundamental units of Le Système international d'unités used to express physical quantities in physics

Scientific notation

A way of expressing numbers in the form a × 10^b, where 1 ≤ a < 10 and b is an integer

Significant figures

The number of meaningful digits in a measurement that indicate the precision of the measurement

Uncertainty

The range of possible values around a measurement that indicates the precision or reliability of that measurement

Distance

The total length of the path traveled by an object, regardless of direction (scalar quantity)

Displacement

The shortest straight-line distance between the starting and ending positions, including direction (vector quantity)

Scalar quantity

A physical quantity that has magnitude only (no direction), such as distance, mass, energy, and speed

Vector quantity

A physical quantity that has both magnitude and direction, such as displacement, velocity, acceleration, and force

Speed

The rate at which distance is covered, calculated as total distance divided by total time (scalar quantity)

Average speed

Total distance traveled divided by total time taken, formula: s_av = d/t

Velocity

The rate of change of displacement with time, including direction (vector quantity)

Average velocity

Displacement divided by time, formula: v_av = s/t

Acceleration

The rate of change of velocity with time, formula: a = (v-u)/t or a = Δv/t

Displacement-time graph

A graph showing displacement (y-axis) vs time (x-axis). Horizontal line = stationary; straight but sloped line = constant velocity; curved line = acceleration/deceleration

Velocity-time graph

A graph showing velocity (y-axis) vs time (x-axis). Gradient = acceleration; area under curve = displacement

Gradient of displacement-time graph

Represents the velocity of the object

Gradient of velocity-time graph

Represents the acceleration of the object

Area under velocity-time graph

Represents the displacement traveled by the object

Force

A push or pull that can change an object's speed, direction, or shape. Measured in Newtons (N)

Newton (unit)

The unit of force, defined as the force required to accelerate a 1 kg mass at 1 m/s²

Contact force

A force applied through direct physical contact, such as friction or collision forces

Non-contact force

A force applied without direct contact, such as gravitational, magnetic, or electrical forces

Net force

The combined effect of all forces acting on an object, calculated by vector addition: F_net = F₁ + F₂

Balanced forces

Forces that are equal in magnitude and opposite in direction, resulting in zero net force

Unbalanced forces

Forces that are not equal in magnitude or direction, resulting in a net force that causes acceleration

Newton's First Law

An object at rest stays at rest, and an object in motion stays in motion at constant velocity, unless acted upon by an unbalanced force

Newton's Second Law

The net force acting on an object equals its mass times its acceleration: F_net = ma

Newton's Third Law

For every action force, there is an equal and opposite reaction force acting on different objects: F_(A on B) = -F_(B on A)

Kinematic equations

Mathematical equations describing uniformly accelerated motion: v = u + at, s = ut + ½at², v² = u² + 2as

Free fall

Motion under the influence of gravity alone, with acceleration due to gravity (g ≈ 9.8 m/s²)

Initial velocity (u)

The velocity of an object at the beginning of a time period

Final velocity (v)

The velocity of an object at the end of a time period

Acceleration due to gravity

The acceleration of objects in free fall near Earth's surface, approximately 9.8 m/s² downward

Linearisation

The process of transforming non-linear data (such as t² vs s) into a linear relationship to find the equation of the trend line

Inertia

A property of matter that keeps something in the same position or moving in the same direction unless acted upon by an external force.