Q31.

Expert-verifiedFound in: Page 44

Book edition
7th

Author(s)
Douglas C. Giancoli

Pages
978 pages

ISBN
978-0321625922

**Determine the stopping distance for an automobile going at a constant initial speed of 95 km/h and a human reaction time of 0.40 s (a) for acceleration **** and (b) for ****. **

(a) The stopping distance is 126.63 m when the acceleration is .

(b) The stopping distance is 68.60 m when the acceleration is .

**The acceleration of an object is defined as the rate at which the velocity of the object changes in a given amount of time.**

**Given data.**

The initial speed of the car is .

The final speed of the car is as it comes to a stop.

Now,

**Rule. **

If during the deceleration of the car, the traveled distance is ,

Then,

.

Here, the car moves at the same speed during the reaction time before applying the brakes.

The reaction time is .

Therefore, due to the reaction time, the car travels a distance of before the application of the brakes.

Now,

(a) When the acceleration is , from equation (i),

Therefore, the stopping distance is 126.63 m when the acceleration is .

(b) When the acceleration is , from equation (i),

Therefore, the stopping distance is 68.60 m when the acceleration is .

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