Question

a cyclist goes once round a circular track of diameter 105meters in 5 minutes calculate it speed

Answer 1

if d is the diameter then perimeter of circle = $\pi$d = $\pi \times 105 = 105 \pi$

time = 5 min = 5 x 60 = 300 sec

Speed = distance/time = $\frac{105\pi}{300} = \frac{7\pi}{20} m/s$

Answer 2

105 m=0.105 km
time=5 min
speed =0.105/5=0.21 km/min