Answer question number nine please.

Question

8.) A 1500-kg automobile, traveling at 5.0 m/s after braking, strikes a power pole and comes to a full stop in 0.1 s. Calculate the force exerted by the power pole and brakes required to stop the automobile.

 

Answer: Change in momentum= F*T

1500(-5m/s) = F(.1)

F=-75,000N

 

9.) For the automobile described in Question 8, explain why a breakaway pole that brings the automobile to rest after 2.8 seconds is safer than the conventional power pole. 

 

Please explain question number nine using physics terms and also use answer for question number eight if needed.

Answer 1

Since the inertia of the car is so large (moving very fast) the impulse by the pole should be large to allow for a greater change in momentum of the car. The change in momentum is equivalent to the impulse created by the power pole, and if the pole takes longer to bring the car to rest, the force used to stop the car is less (as impulse is already fixed by the required change in momentum). Thus, since there is less force required by the pole, the damage on the car is less and is safer.