Question

The puppy needs to catch a train that is moving at 8km/hr. she is 100 meters away and running at 10km/hr. How far will the train have traveled before the puppy is able to jump on?

Answer 1

The given parameters are:

$d = 100m$ -- distance between the puppy and the train

$s_1 = 8km/hr$ -- the speed of the train

$s_2 = 10km/hr$ --- the puppy's speed

Required

The distance where the puppy catch up with the train

First, we calculate the relative speed (rs) of the puppy to the train

$rs =s_2 - s_1$

$rs =10km/hr - 8km/hr$

$rs =2km/hr$

Calculate the time to catch up with the train using:

$Time = \frac{Distance}{Speed}$

$t = \frac{100m}{2km/hr}$

Convert km to m

$t = \frac{100m}{2*1000m/hr}$

$t = \frac{100m}{2000m/hr}$

$t = 0.05hr$

Calculate the distance to catch up with the train using:

$Distance = Speed * Time$

$d= s_2* t$ --- speed of the train multiplied by the time

So, we have:

$d = 8km/hr * 0.05hr$

$d = 8km * 0.05$

$d = 0.4km$

The rabbit will jump on the train at after the train moves 0.4km

Answer 2

8000/3600 = 20/9, 10000/3600 = 25/9, 100/ (25/9-20/9) = 180 seconds 180 * 20/9 = 400 meters