A car is traveling at 100 km/h when the driver sees an accident 80 m ahead and slams on the brakes. What constant deceleration is required to stop the car in ti

Question

A car is traveling at 100 km/h when the driver sees an accident 80 m ahead and slams on the brakes. What constant deceleration is required to stop the car in time to avoid a pileup?

 

 

ANSWER: 62,500 km/h²  ≈ 4.82 m/s²

p350, #77

Answer 1

I fail to see how the proposed answer is correct.

 

We know that 1 km = 1000 meters.

 

At a speed of 100km/h, the vehicle is travelling at 100,000m/h, which, when divided by 3600 seconds / hour = 27.8m/sec

 

A distance or 80m divided by 27.8m/s = 2.9 seconds, less than the proposed deceleration.