Application of Newton's Laws
Figure 2 Car
When these steps are completed a correct free-body diagram will result, and the student can
apply the appropriate equations to the diagram to find the proper solution.
The car in Figure 2 is being towed by a force of some magnitude. Construct
a free-body diagram showing all the forces acting on the car.
Following the steps to construct a free-body diagram (shown in Figure 3), the
object (the car) is chosen and isolated. All the forces acting on the car are
represented with proper coordinate axes. Those forces are:
The force applied to tow the car
The frictional force that opposes the applied force due to the
weight of the car and the nature of the surfaces (the car's tires
and the road)
The weight of the car
The normal force exerted by the road on the car