# Calculating from displacement-time graphs (v=s/t)

I can take readings from displacement-time graphs to find distance, displacement, speed and velocity.

# Calculating from displacement-time graphs (v=s/t)

I can take readings from displacement-time graphs to find distance, displacement, speed and velocity.

## Slide deck

## Lesson details

### Key learning points

- Velocity of an object is equal to the gradient of a displacement-time graph.
- A direction in which velocity and displacement are measured needs to be chosen.
- A negative gradient on a displacement-time graph (sloping downwards) represents velocity in the opposite direction.
- A negative value for displacement represents a position ‘behind’ the starting position.

### Common misconception

A pair of coordinates on a d-t graph can be used to calculate the instantaneous speed or velocity at that point, but that only works for a straight line graph through the origin.

Ask pupils to calculate the velocity of a graph that represents a steady velocity on a line that does not go through the origin, and to check to see if dividing the values at any point on the line gives the right value for velocity.

### Keywords

Displacement-time graph - A displacement-time graph shows the change in displacement over a time period. The displacement along a straight line can be positive or negative.

Gradient - The gradient on a displacement-time graph gives the instantaneous velocity.

Instantaneous velocity - The instantaneous velocity is the velocity of an object at a particular moment in time.

### Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

## Video

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## Worksheet

## Starter quiz

### 6 Questions

a vector measured in m

a vector measured in m/s

a scalar measured in m

a scalar measured in m/s

## Exit quiz

### 6 Questions

a graph showing distance in a given direction over a period of time

the steepness of a line or slope

how fast an object moves in a given direction

how fast an object moves in a given direction over a period of time