Mechanics Review

Flashcards for mechanics concepts including equations of motion, graphs, vectors, Newton's laws, momentum, energy, and power.

Uniform Acceleration Equations

These equations apply when an object is moving with constant acceleration, relating displacement (s), initial velocity (u), final velocity (v), acceleration (a), and time (t).

Displacement (s)

The overall distance travelled from the starting position, including direction (a vector quantity).

Velocity (v)

Rate of change of displacement (Δs/Δt).

Acceleration (a)

Rate of change of velocity (Δv/Δt).

Uniform Acceleration

Where the acceleration of an object is constant.

Area under Acceleration-Time Graph

Represents the change in velocity over time.

Gradient of Velocity-Time Graph

Represents acceleration.

Area under Velocity-Time Graph

Represents displacement.

Gradient of Displacement-Time Graph

Represents velocity.

Instantaneous Velocity

Velocity of an object at a specific point in time, found by calculating the gradient of a tangent to the displacement-time graph.

Average Velocity

Velocity of an object over a specified time frame, found by dividing the final displacement by the time taken.

Scalars

Physical quantities that describe only magnitude (e.g., distance, speed, mass, temperature).

Vectors

Physical quantities that describe both magnitude and direction (e.g., displacement, velocity, force/weight, acceleration).

Resolving a Vector

Splitting a vector into two perpendicular components, vertical and horizontal.

Adding Vectors (Calculation)

Using Pythagoras’ theorem to find magnitude and trigonometry to find direction (for perpendicular vectors).

Adding Vectors (Scale Drawing)

Drawing a scale diagram to find the resultant vector (for vectors at angles other than 90°).

Projectile Motion

The vertical and horizontal components of a projectile's motion are independent and can be evaluated separately using uniform acceleration formulas.

Free-Body Diagram

A diagram showing all the forces acting on an object.

Newton's First Law

An object will remain at rest or travelling at a constant velocity unless it experiences a resultant force.

Newton's Second Law

The acceleration of an object is proportional to the resultant force experienced by the object: F = ma.

Terminal Velocity

Occurs when frictional forces equal driving forces, resulting in no resultant force and constant velocity.

Gravitational Field Strength (g)

The force per unit mass exerted by a gravitational field on an object: g = F/m.

Weight (W)

The gravitational force that acts on an object due to its mass: W = mg.

Newton's Third Law

For each force experienced by an object, the object exerts an equal and opposite force.

Momentum (p)

The product of the mass and velocity of an object: p = mv.

Principle of Conservation of Linear Momentum

Momentum is always conserved in any interaction where no external forces act.

Moment of a Force

Force multiplied by the perpendicular distance from the line of action of the force to the point: Moment = Fx.

Principle of Moments

For an object in equilibrium, the sum of anticlockwise moments about a pivot equals the sum of clockwise moments.

Centre of Gravity

The point at which gravity appears to act on an object.

Work Done (W)

Force causing a motion multiplied by the distance travelled in the direction of the motion: W = FΔs or W = Fs cos θ.

Kinetic Energy (Ek)

Energy that an object has due to its motion: Ek = (1/2)mv^2.

Gravitational Potential Energy (Egrav)

Energy that an object has due to its position in a gravitational field: ΔEp = mgΔh.

Principle of Conservation of Energy

Energy cannot be created or destroyed, but can be transferred from one form to another. Total energy in a closed system stays constant.

Power (P)

The rate of energy transfer: P = E/t or P = W/t.

Efficiency

A measure of how efficiently a system transfers energy: Efficiency = (useful power output)/(total power input) or (useful energy output)/(total energy input).