Review: Forces and changes in motion
Build force diagrams, combine opposite forces, and explain motion with a stated model.
Bring the unit skills together
Use these 4 new cases to check your reasoning. Choices are temporary and are not saved to an account, sent to staff or recorded as school grades. Download your current review choices before leaving or reloading.
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Use the skills in a new task
Repair a pretend toy-cart explanation. It says “6 units right and 2 left make it speed up right,” but a complete force list adds 4 left units of friction. The cart starts moving right. Draw or describe the full diagram, find the net, explain its motion, then change friction to 5 left units.
Work on paper or in your own document. Explain the choices you made.
- Include all three forces and sum the left forces.
- Find zero net for the original complete list.
- Describe continued constant right velocity under the model.
- For changed friction, find 1 unit left and initial slowing.
Compare with a model response
The complete diagram has 6 right, 2 left pull, and 4 left friction. Left total is 6, so the net is zero. The cart already moves right, so it continues right at constant speed while the stated forces hold. If friction becomes 5, the left total is 7 and the net is 1 left. Its velocity then changes leftward, initially slowing its rightward motion.
A different response can also meet the criteria. Compare the evidence and reasoning, rather than copying the wording.