1. Solving for a Different Quantity.
Using the context given in the video above, find the magnitude of the normal force acting on the skateboarder.
Section 3.9 Force Analysis for a Single System
At this point, you have approached several A*R*C*S contexts using the steps in Figure 2.16.1, mostly by analyzing the motion of a system. Now you need to be able to use the same structure when analyzing the forces acting on a system. The steps below can be extremely helpful.
Analyze and Represent: Identify a system and draw a Free-body Diagram.
Calculate: Is the acceleration \(0 \mathrm{~m/s^2}\) (static or dynamic equilibrium) or not \(0 \mathrm{~m/s^2}\) (dynamics)? Once you know, use the Law of Motion!
Sensemake: All the sensemaking strategies you have will work, but a new strategy called Special-case Analysis (see Section 3.10) can be especially useful.
Exercises Activities: Practice with Force Analysis
2. Exploring Systems of Equations.
It is very common in physics (and especially when using Force Analysis) to end up with a system of equations. Suppose you are in the middle of using Force Analysis and you end up finding a system of two equations that contain three different unknown quantities. How do you think you could make further progress on such a problem?
3. Practice with Force Analysis.
A child in a wagon is trailing a large kite behind her at a low angle while her father pulls the wagon forward so it moves at constant speed. Find the force the father exerts on the wagon.
Tip.
Model both the force from the kite and the force from the father as constant. (Don’t forget to use the A*R*C*S format along with the steps above!)
