Question

question 18 (1 point)
can an object with a constant 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 slowing down.
yes, this is possible, and a cradle thrown straight up is an example.
yes, this is possible, and a car that starts from rest, speeds up, slows down to a stop, and then backs up is an example.
page 18 of 20

Explanation:

To determine if an object can change direction with constant acceleration, recall that acceleration is the rate of change of velocity (including direction). For example, a ball thrown upward has constant acceleration (due to gravity, \(a = -g\)) and changes direction at the peak. Option C says "Yes, this is possible, and a ball that starts from rest, speeds up, slows down to a stop and then backs up is an example" – but actually, a simpler example is projectile motion (thrown ball) or a car moving forward, braking (decelerating, constant acceleration magnitude) to reverse direction. Wait, no – the correct reasoning: acceleration is constant in magnitude and direction (e.g., gravity). When velocity and acceleration are in opposite directions, the object slows down, reverses direction, and then speeds up in the new direction. So the correct option is the one that says "Yes, this is possible..." (the third option, C? Wait, the options:

Option 1: No, not possible (wrong).

Option 2: No, because it always speeds up (wrong – acceleration can be opposite to velocity, causing slowing down).

Option 3: No, it never turns (wrong – it can turn, like circular motion? Wait no, circular motion has centripetal acceleration, which is changing direction, so acceleration isn't constant in direction. Wait, no – constant acceleration means magnitude and direction of acceleration are constant. So a ball thrown vertically: acceleration is constant (\(g\) downward). Velocity is upward, then zero, then downward – so direction changes. So the correct option is the one that says "Yes, this is possible..." (the fourth option? Wait the user's options:

Looking at the options:

1. No, this is not possible because it is always speeding up. (Wrong)

1. No, this is not possible because it is always speeding up or slowing down. (Wrong)

1. No, it is never able, and a car turning a corner is an example (but turning a corner has centripetal acceleration, which is changing direction, so acceleration isn't constant. So this is wrong)

1. Yes, this is possible, and a ball that starts from rest, speeds up, slows down to a stop and then backs up is an example. Wait, but a ball starting from rest, with constant acceleration? No – if acceleration is constant, to slow down to a stop and reverse, acceleration must be opposite to velocity. Wait, maybe the example is a bit flawed, but the key is that constant acceleration (magnitude and direction) can cause direction change. So the correct option is the fourth one (the one with "Yes, this is possible...").

Wait the user's selected option is the fourth one (blue). Let's confirm:

Acceleration is constant (e.g., \(a = -5 \, \text{m/s}^2\) constant). Object starts moving, velocity is positive, acceleration negative: slows down, stops, then velocity becomes negative (backs up) – so direction changes. So the correct option is the one that says "Yes, this is possible, and a ball that starts from rest, speeds up, slows down to a stop and then backs up is an example."

Answer:

The correct option is the fourth one (the one with the text: "Yes, this is possible, and a ball that starts from rest, speeds up, slows down to a stop and then backs up is an example.").