Question

The odometer of a car reads 2000 km at the start of a trip and 2400 km at the end of the trip. If the trip took 8 h, calculate the average speed of the car in km h-1 and m s-1.​

Answer 1

Given :
Distance = final reading of odometer - initial reading of odometer = 2400km - 2000km = 400km
Total time = 8hrs
Average speed = Total distance covered / total time taken = 400/8 = 50 km / hr
Now in m/s
50x5/18= 250/18 = 13.8888... = 13.9 m/s

Answer 2

Distance travelled : 2400km - 2000km = 400km

Time taken : 8 hours

$\sf \: average \: \: speed = \huge \frac{u + v}{2} \times t$

$\sf v_{avg} = \frac{400}{2} \times 8 \\ \\ = \sf \: 200 \times 8 \\ \\ \sf \pink{= 1600 \frac{km}{h} }$

$\sf \: to \: \: convert \: \: \frac{km}{h} \: \: to \: \: \frac{m}{s} \: \: speed \: \: is \\ \sf \: multiplied \: \: by \: \: \red{ \frac{5}{18} } \\ \\ \\ \\ \sf \: = 1600 \times \frac{5}{18} \\ \\ \sf \: = \frac{800 \times 5}{9} \\ \\ \sf \: = \frac{4000}{9} \\ \\ \pink{\sf = 444.4 \frac{m}{s} }$