Physics · Forces and Motion

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. Hence, the correct option is C.

If the car is speeding up, its velocity is negative (because south is negative) and its acceleration is also negative because final velocity is greater than initial velocity, and the sign of final velocity is negative. Hence, this option is incorrect because in this case, velocity is not positive. 

If a car is moving at a constant speed, in the south direction, its velocity is negative (because south is negative), and there is no acceleration because speed is constant. Hence, both conditions are not satisfied and this option is incorrect. If a car is moving at a constant speed, in the south direction, its velocity is negative (because south is negative), and there is no acceleration because speed is constant. Hence, both conditions are not satisfied and this option is incorrect. 

As the car is moving in the north direction, its velocity is positive. But due to it being slowed down, the acceleration is negative. It compliments the given situation, and hence, this option is correct. 

As a car slows down, its velocity is negative because it is moving southward. Moreover, as it is slowing down, its acceleration is also negative. Hence, it does not match the given statement, and the option is incorrect.