# Homework Help: Newton's second law for car force problem

1. Feb 16, 2005

### Kahsi

Hi.

I have this problem:

The fastest cars can travel at 350km/h. When you take the foot of the gaspedal the air will decrease the speed of the car. This leads to a retardation (I hope it's the right word for it) at 1.1 g. Which force (N) will affect the driver (80kg)? The weight of the car is 600 kg.

Which formula should I use? I don't want anyone to give me the answer just like that, instead I would like some tips.

Thank you in advance

2. Feb 16, 2005

### Gamma

Use the newton's second law to find the decelaration of the (car +driver) system. Again apply the same law to the driver alone using the above found decelaration to find the force on him.

3. Feb 16, 2005

### Nylex

You mean mass.

4. Feb 16, 2005

### Kahsi

Yea, mass. Sorry.

Newtons second law

F = m * a

I have m (the mass) But I don't have the acceleration or the Force.

5. Feb 17, 2005

### vincentchan

the 1.1g is the accelaration,
1g=9.8 m/s^2