Non-Uniform Motion (GCSE Physics)

Non-Uniform Motion

Non-Uniform Motion

For exams, we need to be able to calculate the average speed of an object with non-uniform motion.

In these types of questions, we can still apply the formula that we have just learnt; s = vt. The only difference is that we have to calculate the total distance and time, as shown in the following example.

Question: Josh is going on a bike ride. He starts off on a well-paved road, where he cycles 500m in 70s. He then comes to an uphill stretch, where he cycles a distance of 450m in 95 seconds. Calculate his average speed in m/ s and give your answer to 1dp.

1. Calculate the total time taken for the journey.

In this case, we need to add up

70 and 95.
70 + 95 = 165 seconds
839

2. Calculate the total distance travelled.

Again, we just have to add up 500 and 450.
500 + 450 = 950 metres

3. Use the formula.

We know that s = vt, but for this question we need to rearrange to find the speed.

s = vt
v = s/t
v = 950 / 165
v = 5.757575… m/s
v = 5.8 m/s (1dp)