Question

question 18 (1 point)
can an objects velocity change direction when its acceleration is constant? support
your answer with an example.
○ no, this is not possible because it is always speeding up.
○ no, this is not possible because it is always speeding up or always slowing down,
but it can never turn around.
○ yes, this is possible, and a rock thrown straight up is an example.
○ yes, this is possible, and a car that starts from rest, speeds up, slows to a stop,
and then backs up is an example.
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Explanation:

To determine the correct answer, we analyze each option:

1. First option: Incorrect. An object with constant acceleration can change velocity direction (e.g., projectile motion or a rock thrown up). It's not always speeding up.
2. Second option: Incorrect. An object with constant acceleration can reverse direction (like a rock thrown upward, which slows, stops, then falls down with constant acceleration due to gravity).
3. Third option: Correct. A rock thrown straight up has constant acceleration (gravity, \(a = -g\) if upward is positive). Its velocity is upward initially, slows to zero at the top, then becomes downward (changing direction) while acceleration remains constant.
4. Fourth option: Incorrect. A car that starts from rest, speeds up, slows to a stop, and then backs up does not have constant acceleration throughout (the acceleration changes when it slows to a stop and then reverses; constant acceleration would mean the acceleration magnitude and direction are unchanging, so the car example does not have constant acceleration).

Answer:

C. Yes, this is possible, and a rock thrown straight up is an example.