Unit 1 Practice Quiz, with Socrates

1. A student writes: the car’s speed is \(-15\ \mathrm{m/s}\). What is wrong with that statement?

1. Nothing. Speed is negative whenever an object moves in the negative direction.
2. Speed is a scalar, so it carries magnitude only and cannot be negative.
3. The magnitude is wrong; it should be 15 m/s only if the car is slowing down.
4. Speed must be reported in km/h, not m/s.

2. A runner completes exactly one lap of a 400 m oval track and finishes where she started. Her distance traveled and the magnitude of her displacement are, in that order,

1. 400 m and 400 m
2. 400 m and 0
3. 0 and 400 m
4. 0 and 0

3. Two objects, P and Q, are shown on the same position against time graph. Both are straight lines, and P’s line is steeper than Q’s. Which statement must be true?

1. P is farther from the origin than Q.
2. P has a greater speed than Q.
3. P has a greater acceleration than Q.
4. P began moving before Q did.

4. A car travels east and is slowing down. Taking east as positive, the signs of its velocity and its acceleration are, in that order,

1. positive and positive
2. positive and negative
3. negative and positive
4. negative and negative

5. Two carts have velocity against time graphs of different shapes over the same time interval. Neither graph goes below the time axis, and the two enclose equal areas with it. Which quantity must be the same for both carts?

1. Their accelerations.
2. Their final velocities.
3. Their displacements.
4. Their initial velocities.