Unit 2 Topic 1 - Linear motion

Scalars

Quantities that have magnitude but no direction.

Vectors

Quantities that have both magnitude and direction.

Distance

The total length of the path travelled by an object, regardless of direction.

Displacement

The distance travelled by an object in a specific direction.

Speed

The rate at which distance changes in meters per second.

Velocity

The rate at which displacement changes, with an included direction, in meters per second.

Acceleration

The rate of change of velocity.

Force

A push or pull upon an object that results from the object's interaction with another object.

Upthrust

The push upwards of something in a fluid.

Friction

The resistive force between two moving objects that are in contact or a moving object in contact with a stable object.

Air resistance

The push upwards of air as something falls through it.

Drag

A resistive force that acts in the opposite direction of an object moving through a fluid.

Normal force

The upwards force that is perpendicular to a surface.

Tension

The pulling force acting on a wire when it is pulled tight by forces acting from opposite ends.

Electrostatic force

The push or pull of charged particles.

Magnetic force

The push or pull force exerted by magnets or electrically charged particles.

Weight

The effect of gravity on an object's mass.

Inertia

The reluctance of a body to change its velocity.

Newton's first law

Objects in motion tend to stay in motion and objects at rest tend to stay at rest unless acted upon by an opposing external unbalanced force.

Newton's second law (definition)

The direction of the acceleration of an object is in the direction of the net external force acting on it and proportional to the size of the force and inversely proportional to the mass.

Newton's second law (formula)

F = ma, where F is the net force acting on an object, m is the mass of the object and a is the acceleration of the object.

Air resistance proportionality

The air resistance acting on an object is directly proportional to the square of the speed of the object.

Terminal velocity

The top speed an object can reach when falling through a gas or liquid.

Newton's third law

Every action has an equal and opposite reaction.

Momentum

The product of a body's mass and velocity, represented by the formula p = mv, measured in units kg/m/s.

Impulse

The change in an object’s momentum from one point in time to another.

Law of conservation of momentum

The total momentum of an isolated system remains constant if no external forces act on it.

Energy

A property of matter and systems that describes the capacity to do work or cause a change.

Work

The energy transferred to or from an object when a force acts on it while it moves a distance.

Potential energy

Stored energy that an object or system has because of its position, shape or arrangement relative to other objects within a force field.

Gravitational potential energy

The stored energy an object has because of its place in a gravitational field.

Kinetic energy

The energy an object has because of its motion.

Power

The rate a which work is done or energy is transferred over time.

Impulse (formula)

I = ΔF*t = m*Δv, where ΔF is the net force applied to an object, t is the duration the force is applied for, m is the mass of the object and Δv is the change in velocity.

Work done by a force on an object

W = F*S*cos(x), where F is the applied force, S is the displacement of the object and x is the angle between the force and displacement.

Elastic interactions

Interactions where momentum and kinetic energy are conserved with no dissipation to other forms of energy.

Inelastic interactions

Interactions where momentum is conserved but some kinetic energy of the colliding particles is transformed into other forms of energy.

Completely inelastic interactions

Interactions where the colliding objects stick together after impact, maximising the loss of kinetic energy.