Question

A man drives for 30 minutes at a speed of 25m/s, then stops for 10 minutes, and finally drives for 20 minutes at 36 m/s. Calculate (a) the total distance traveled and (b) the average speed

Answer 1

Part a

He firstly travels for 30 mins at 25 m/s

i.e. he travels for $30 \times 60 = 1800 seconds$

The distance he travels will be $1800 \times 25 =45000 m (45 km)$

His second set of travelling is for 20 minutes at 36 m/s

i.e. he travels for $20 \times 60 = 1200 seconds$

The distance he travels will be $1200 \times 36 = 43200 m (43.2 km)$

The total distance he travels will be $45000 + 43200 = 88200 m.$

Part b

This means his average speed as the overall journey took one hour is

$S= \frac{D}{T}= \frac{88200}{3600} = 24.5 m/s\\$