# Case and Truck

1. Sep 19, 2007

### azila

1. The problem statement, all variables and given/known data
A 20.0 kg packing case is initially at rest on the floor of a 1400-kg pickup truck. The coefficient of static friction between the case and the truck floor is 0.30, and the coefficient of kinetic friction is 0.20. Before each acceleration given below, the truck is traveling due north at constant speed.

A. Find the magnitude of the friction force acting on the case when the truck accelerates at 2.27 m/s^2 northward.

B. Find the direction of the friction force acting on the case when the truck accelerates at 2.27 m/s^2.

2. Relevant equations
Fk = (coefficient of kinectic)N
Fs = (coefficient of static)N
F = ma

3. The attempt at a solution

Ok, first of all when I calculate the weight, I would combine the masses of the truck and the case right? should I use the F=ma formula and plug in the masses and acceleration. Find the force. Now, what do I do?? This is where I am confused. If you can help, I would appreciate it. thanks in advance.

2. Sep 19, 2007

### learningphysics

What are the forces acting on the case? Is the case sliding in the truck... or is it not sliding?

3. Sep 19, 2007

### azila

the case is not sliding..........it is just sitting in the truck;

4. Sep 19, 2007

### learningphysics

Ok. What are the forces acting on the case? Write the $$\Sigma\vec{F} = m\vec{a}$$ equation for the case.