# Driver and Car

1. Oct 23, 2007

### Ryo124

1. The problem statement, all variables and given/known data

A car starts from rest at a stop sign and accelerates to speed 15m/s in a time of 6 seconds. The mass of the car is 300kg and the mass of the rider is 100kg. What is the force on the rider?

2. Relevant equations

I figured the acceleration to be 2.5m/s/s. And I know that F = ma.

3. The attempt at a solution

I'm not sure if you calculate the force on the car and the driver (400kg), or just the force on the driver (100kg).

So the equation is either F=(100)(2.5) or F=(400)(2.5). Which one? Do the car and driver act as one mass?

Last edited: Oct 23, 2007
2. Oct 23, 2007

### Dick

It asks for "the force on the rider". Not the car.

3. Oct 23, 2007

### Ryo124

I just thought that the driver was in system with the car, so their masses would add up? Is that ever the case?

4. Oct 23, 2007

### Dick

If they ask you for the total force you need to push the car AND driver (i.e. how much force does the engine need to provide) then you would add them.