Year 10 Physics - Revision.

Distance

Total path travelled.

Displacement

Straight-line change from start to finish.

Speed

How fast something moves; Speed = distance ÷ time.

Velocity

Speed with direction.

Acceleration

Change in velocity over time; a = (v − u) ÷ t.

Displacement–time graph

Slope = velocity.

Ticker tape — fast

Dots far apart.

Ticker tape — slow

Dots close together.

Ticker tape — slowing

Dots get closer.

Newton’s First Law

Objects stay still or move at constant speed unless a force acts.

Newton’s Second Law

F = m × a.

Newton’s Third Law

Every action has an equal and opposite reaction.

Balanced forces

No acceleration.

Unbalanced forces

Causes acceleration.

Weight

W = m × g.

Reaction force

Upward force balancing weight when stationary.

Spectral order

O B A F G K M (hottest → coolest).

O‑type

Blue, hottest.

B‑type

Blue‑white, very hot.

A‑type

White, hot.

F‑type

Yellow‑white.

G‑type

Yellow (Sun).

K‑type

Orange.

M‑type

Red, coolest.

Apparent magnitude

Brightness from Earth.

Absolute magnitude

Actual brightness.

Left side of H–R Diagram

Hot stars.

Right side of H–R Diagram

Cool stars.

Top of H–R Diagram

Bright stars.

Bottom of H–R Diagram

Dim stars.

Main sequence

Diagonal band; most stars.

Giants / Supergiants

Top‑right; cool but bright.

White dwarfs

Bottom‑left; hot but dim.

Big Bang Theory

Universe began from a single point; expanding.

Evidence for Big Bang

Red‑shift.

Steady State Theory

Universe always existed; matter created continuously.

Hubble’s Law

Further galaxies = more red‑shift.

Red‑shift

Light stretched → moving away.

Age of universe

~14 billion years.

Parsecs

Unit of distance.

Gradient

rise ÷ run.

Distance–time graph gradient

Speed.

Fastest section on a graph

Steepest slope.

Slowest section on a graph

Flattest slope.

Line of best fit

Smooth line showing trend.

Good graph features

Labels, scale, accurate points, best‑fit line.