Question

what is the si unit of acceleration?
○ m/s
○ m/s²
○ m/s
○ m/s
question 7
1 pts
when a cars velocity is negative and its acceleration is negative, what is happening to the cars motion?
○ the car travels at constant speed.
○ the car slows down.
○ the car speeds up.
○ the car remains at rest.
question 8
1 pts
when a cars velocity is positive and its acceleration is negative, what is happening to the cars motion?
○ the car remains at rest.
○ the car slows down.
○ the car travels at constant speed.
○ the car speeds up.

Explanation:

Step1: Recall SI unit of acceleration

Acceleration is change - in - velocity per time. Velocity has SI unit of m/s and time has SI unit of s. So acceleration SI unit is $\frac{m/s}{s}=m/s^{2}$.

Step2: Analyze case of negative velocity and negative acceleration

When velocity and acceleration have the same sign, the speed of the object increases. Since both are negative, the car speeds up in the negative direction.

Step3: Analyze case of positive velocity and negative acceleration

When velocity and acceleration have opposite signs, the object slows down. So the car with positive velocity and negative acceleration slows down.

Answer:

Question 1: m/s²
Question 7: The car speeds up.
Question 8: The car slows down.