2. A force is a push or pull. Net force is the combination (sum) of all acting forces.

3. 90° The Normal Force is perpendicular to the surface.

4. The Net Force is 10N. 40N + (-30N) = 10N

5. Yes! If it moves at a constant velocity in a straight line. Then ΣF = 0.

6. Magnitude And Direction

7. It means that the sum of all the forces that act on an object in equilibrium equal zero.

8. Scalar quantity is measured by magnitude only; a number. Vector quantity needs both magnitude and direction for its description.

9. Both forces are equal in magnitude, but opposite in directions. Thus, the net force is zero.

10. Force and velocity are vector quantities. Time, area, and volume are scalar quantities.

11. The net force is zero, as the rule ΣF = 0 states.

12. It is correct to say no net force, as both gravity and the normal force of the floor act on the cat.

13. The maximum will occur when the forces are in the same direction – so 20N +12N = 32N. The minimum will occur when they are in opposite directions – so 20N + (-12N) = 8N.

14. The sum of all the forces (net force) must equal zero. Yes, it must be zero if it is in mechanical equilibrium.

15. Agree! If only a single force acts on it, it will not be in equilibrium. There must be one or more additional forces to produce zero net force for equilibrium.

16. There are two: Weight and the Normal Force.

17. Yes – It is not undergoing a change in motion. The force if the moving puck is equal but opposite the frictional force between the ice and hockey puck.

18. 200N. Since it is moving at a constant speed in a straight line, it is in equilibrium. Therefore, the force Alyssa puts on the crate is the same as the force of friction.