Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
For each force, name its third-law partner and the object it acts on.
Newton's third law: when A pushes B, B pushes A with a force of the same size in the opposite direction. The two forces act on different objects, so they never cancel each other.
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) The nail pushes back on the hammer.
Step 2. (b) The ball pushes back on the boy's foot.
Step 3. (c) The Moon pulls the Earth.
Step 4. (d) The water pushes the swimmer forward.
Answer: Each partner acts on the first object, with the same size and opposite direction.
Log in to join the discussion.
Loading…