Question

why does the definition of force include the words \may\ and \change?\ forces dont always cause motion, and some forces act to decrease the velocity of an object. all of these are true. forces only act sometimes, and when they do, they change very quickly. forces always act to change the direction of objects but may not be able to be calculated.

Explanation:

• Forces don't always cause motion. For example, when you push against a wall, the wall doesn't move.
• Forces can decrease the velocity of an object. Friction is a force that acts opposite to the direction of motion and slows down moving objects.
• The statement "Forces only act sometimes, and when they do, they change very quickly" is incorrect. Forces can act continuously (like gravitational force acting on objects on Earth at all times).
• The statement "Forces always act to change the direction of objects but may not be able to be calculated" is wrong. Forces can act to change speed (not just direction) and forces can be calculated using Newton's laws (e.g., \(F = ma\)).

Answer:

B. All of these are true.