The following words used to complete the blank spaces come from the definitions:
1. When forces are balanced, pulling in opposite directions with equal size, we say they are in equilibrium.
2. A force which resists the relative motion of two bodies in direct contact is called friction.
3. When work is done, we know because there is displacement.
4. A force is any push or pull in a direction.
5. There is a force which resists changes in motion, called inertia.
6. We know we have exerted a force even when we have done no work. This is called effort.
7. Force * Displacement equals work.
8. When a force causes motion, we know work has been done.
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