SME
Grade 8 Science
Newton's three laws of motion
The main lesson, then each kind of problem it solves.
Newton's three laws of motion
Main lesson
Two skaters push apart: force pairs
Use this for “Two skaters push off each other. Who moves, and who speeds up more?”
Net force: a pull against friction
Use this for “A 50 N pull against 30 N of friction on an 8 kg box. What is the acceleration?” and “Why must you keep pushing to keep a box sliding at a steady speed?”
Balanced or unbalanced forces?
Use this for “What causes the sliding rock to slow down?”