# Kinematics - Mother catching up on child

1. Apr 28, 2007

### batman

1. The problem statement, all variables and given/known data
A boy runs out the door and starts down the road for school at 10km/h. Six minutes later,his mother discovers that he has forgotten his lunch, and she runs after him at 14km.h.

a) How far des he get in 6.0min?
b) How long does it take her to catch him, in minutes?
c) How far from home is he when shes cathes him?

2. Relevant equations
Have no idea what equations to use sme thing about position and time.

3. The attempt at a solution

The answers are 1.0km, 15 minutes and 3.5km. CAn someone show me how you would go about solving this question?

2. Apr 28, 2007

### Pyrrhus

If the velocity is constant (direction and magnitude), and you know v = dx/dt

x = vt for the start from rest case.

3. Apr 29, 2007

### raman911

$$R= \frac{v}{I}$$
$$= \frac{V_{2}- V_{1}}{I_{2} - I_{1}}$$
$$= \frac{4.5V- 1.5V}{46.8A -15.6A}$$

$$= \frac{4.5V- 1.5V}{21A -7A}$$

Last edited: Apr 29, 2007