Question

If north is the positive direction, which situation involves positive velocity and negative acceleration?

• A. A car speeding up as it moves southward
• B. A car moving southward at a constant speed
• C. A car slowing down as it moves northward
• D. A car slowing down as it moves southward

Answer 1

Answer: (C)

A car slowing down as it moves northward

The rate of change of velocity with respect to time is known as acceleration. Negative acceleration means a decrease in velocity with respect to time.

If a car is moving northward and slowing down, the displacement will be along the north (positive), so the velocity will be positive until it gets stopped. As the car is slowing down, the acceleration will be negative.