Question

m fri sep 12
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the acceleration at a is positive and less than the acceleration at b.
the acceleration at b is positive and less than the acceleration at a.
the accelerations at a and b cannot be determined.
the accelerations at a and b are each zero.
question 4
when a cars velocity is negative and its acceleration is negative, what is happening to the cars motion?
the car remains at rest.
the car travels at constant speed.
the car slows down.
the car speeds up.
question 5
motion of ball moving on ramp

Explanation:

Step1: Recall velocity - acceleration relationship

Acceleration is the rate of change of velocity. If velocity $v$ and acceleration $a$ have the same sign, the speed of the object increases. If they have opposite signs, the speed decreases. If $a = 0$, the speed is constant (assuming no non - acceleration related forces like friction etc. acting to change speed). If $v=0$ and $a = 0$, the object is at rest.

Step2: Analyze Question 4

The car has negative velocity and negative acceleration. Since they have the same sign, the magnitude of the velocity (speed) is increasing. So the car is speeding up.

Answer:

Question 4: The car speeds up.