physics easy memorisation

What does the gradient of a displacement–time graph show?

Velocity (slope = velocity).

How do you find velocity on a displacement–time graph?

Velocity = change in displacement ÷ change in time.

What does a flat line mean on a displacement–time graph?

The object is stationary.

Can you find acceleration from a displacement–time graph?

No – you need a velocity–time graph for that.

What does the gradient of a velocity–time graph show?

Acceleration

How do you find displacement on a velocity–time graph?

Displacement = area under the graph.

What does a horizontal line mean on a velocity–time graph?

Constant velocity (acceleration = 0).

How do you find speed from a velocity–time graph?

Speed = total area under graph ÷ total time.

What does the y-value represent on an acceleration–time graph?

Acceleration.

How do you find change in velocity from an acceleration–time graph?

Change in velocity = area under the graph

What does a flat line above the x-axis mean on an acceleration–time graph?

Constant positive acceleration.

(s-t) What does a negative displacement mean?

The object is on the opposite side of the starting point.

(s-t) What does a negative gradient (downward slope) mean?

Moving back toward the start (negative velocity).

(v-t) What does negative velocity mean?

The object is moving in the opposite direction.

(v-t) How do you find displacement if the velocity–time graph goes below the x-axis?

Find the area above and below the x-axis separately; areas below are negative.

(v-t) What if total area is negative on a velocity–time graph?

The displacement is in the negative direction.

(v-t) How do you find distance from a velocity–time graph with negative areas?

Add absolute value of all areas (make them positive before adding).

(a-t) What does negative acceleration mean?

Deceleration (slowing down) or acceleration in the opposite direction.

(a-t) What does area under a negative acceleration–time graph represent?

Negative change in velocity (slowing down or reversing direction).