Application of Newton's Laws
FREE-BODY DIAGRAMS
Rev. 0
Page 7
CP-04
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.
Example:
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.
Solution:
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:
F
-
The force applied to tow the car
app
F
-
The frictional force that opposes the applied force due to the
K
weight of the car and the nature of the surfaces (the car's tires
and the road)
W
-
The weight of the car
N
-
The normal force exerted by the road on the car
