Acceleration and Deceleration

Back to Physics Grade 9/10

Description

This is a simple physics calculation tutorial aimed at high school students in grades 9 and 10 (GCSE, HSC) that runs through the concept of acceleration and deceleration, and positive and negative acceleration. Video tutorial to come shortly.

What is acceleration and deceleration?

When an object accelerates, its velocity changes. In everyday language (and for the purpose of this GCSE-level tutorial), we will say that an object speeds up when it accelerates. Deceleration is the term we use for an object that is slowing down. For this tutorial, we will not concern ourselves with acceleration that causes changes in direction.

Acceleration Example

A person who starts jogging from standing still looking towards the East, goes from 0 m/s to 3 m/s East in 2 seconds. Calculate the acceleration required for this change in velocity.

Acceleration = (velocityfinal - velocityinitial) ÷ time
Acceleration = (3 m/s - 0 m/s) ÷ 2 s
Acceleration = 3 m/s ÷ 2 s
Acceleration = 1.5 m/s2, in the Easterly direction

In this scenario, the calculated acceleration is positive, indicating that the person has undergone positive acceleration i.e. sped up.

Deceleration Example

A bus travelling at 14 m/s Easterly comes to a stop in 5 seconds. Calculate the deceleration required for this change in velocity.

Acceleration = (velocityfinal - velocityinitial) ÷ time
Acceleration = (0 m/s - 14 m/s) ÷ 5 s
Acceleration = -14 m/s ÷ 5 s
Acceleration = -2.8 m/s2, in the Easterly direction

In this scenario, the negative sign in front of the 2.8 m/s2 indicates the person has undergone deceleration i.e. slowed down.

Exercise Worksheet

This worksheet has five exercises that you can work through in your own time, with answers given in meters per second, kilometers per hour and miles per hour. To download the document visit Slideshare here: