What average force is it brought to rest?

[missashley]

Homework Statement

Auto companies frequently test the safety of automobiles by putting them through crash tests to observe the integrity of the passenger compartment. If a 1000. kg car is sent toward a cement wall with a speed of 14 m/s and the impact brings it to a stop in 8.00 * 10^-2 seconds, with what average force is it brought to rest?

Homework Equations

F = mv/t

The Attempt at a Solution

F = mv/t = (1000*14)/(8e-2) = 175000 N

 

[dynamicsolo]

F = mv/t = (1000*14)/(8e-2) = 175000 N

There you have it! The average acceleration during the simulated crash is the change in velocity (14 - 0 m/sec) divided by the time interval over which it occurred (0.08 sec) or 175 m/(sec^2) , which is almost 18 times the acceleration of gravity. The average force on the car is then its mass times that average acceleration or

175 m/(sec^2) · 1000 kg = 175,000 N (or almost 18 times the car's weight).

 

[chaoseverlasting]

Thats right.