Chapter 2, Problem 39R

To determine

To Choose: The correct option.

Answer to Problem 39R

Option (A) is the correct answer.

Explanation of Solution

Formula used:

The equation of motion is,

  $v=u+at$ ........ (1)

Here, $v,u$ , $t$ and $a$ are final velocity, initial velocity, time and acceleration.

Calculation:

Rearranging the equation (1),

  $a=\frac{v-u}{t}$ ........ (2)

The car would possess an acceleration when it start from rest to attain top speed or coming down from the top speed to halt. It also has acceleration when it speed is constant but change in direction.

So, the option (B), (C) and (D) are wrong.

The car doesn’t have acceleration only when the speed is constant without change in direction or it is at rest.

Conclusion:

Hence, a car moves at $\text{80}\text{km/h}$ on a flat, straight highway, under this condition, car doesn’t get accelerated.