Question

What is the acceleration of a car that travels in a straight line at a constant speed?

Answer 1

Zero

Explanation:

Acceleration is defined as the rate of change of velocity.

In the given problem the car travels in a straight line at a constant speed.

Acceleration `vec a-=(dvecv)/dt`
Clearly `(dvecv)/dt=0`
Or there is zero acceleration of the car.

If we consider the retarding force created by friction or air resistance then we can say that its acceleration is retarding force divided by mass of the car