Force and motion II extends force and motion I to forces at angles and to springs. The lessons start with splitting a force into two parts and finish with reading a graph of a spring.
This cluster is part of SPM Physics. It builds on force and motion I, especially the lesson on drawing force diagrams.
What does one situation need?
Consider this example. A 20 N force pulls a box along a floor at 30° above the horizontal, and the box is attached to a spring that stretches by 4.0 cm.
Components. The horizontal part of the pull is 20 cos 30° ≈ 17.3 N, and the vertical part is 20 sin 30° = 10 N. Equilibrium. If the box does not move, the spring force equals the horizontal part of the pull and friction is zero in this simplified version.
Hooke’s law. A force of 17.3 N stretching a spring by 0.040 m gives k = 17.3 ÷ 0.040 ≈ 430 N m⁻¹. The same box needs three lessons, each one supplying a number for the next.
How do the lessons connect?
- Resolving forces into components splits one force into two perpendicular parts.
- Combining forces and finding a resultant joins forces into one.
- Applying equilibrium conditions uses both to solve for unknown forces.
- Using Hooke’s law and elastic energy covers springs.
- Interpreting force-extension graphs reads the spring from data.
The chapter practice set mixes all five with explained answers.
Who should start where?
If you choose sine or cosine by memory, begin with components. If you can resolve but get stuck on hanging objects, go to equilibrium. If springs and graphs are the trouble, start with Hooke’s law and the graph lesson. You can follow the year order in the Form 5 learning route.
A teacher can work from your own mistakes if you want that. See online one-to-one Physics tuition for how lessons start.