Question

A cheetah is running at 100. km/hr directly after an antelope which is running at 90.0 km/hr. Assuming both animals run in a straight line, and the antelope is 10.0 m ahead, how long will it take for the cheetah to catch the antelope?

Answer 1

The reletive speed of the cheetah with respect to the antelope is $100km/h-90km/h = 10km/h=10000m/h$. Thus the cheetah will cover the separating distance of 10m in

$$t = \dfrac{10m}{10000m/h} = 0.001h = 3.6s$$

Answer. 3.6s.