posted by Haley on .
A 4.00 103-kg car has a speed of 9 m/s. The car then hits a tree. The tree doesn't move and the car comes to rest.
(a) Find the change in kinetic energy of the car.
(b) Find the amount of work done in pushing in the front of the car.
(c) Find the size of the force that pushed the front of the car in 50 cm.
- i got -2.00e+05 for the first answer and -4.00e+05 for the third, but neither worked?
ΔKE =KE2 – KE1 = 0 - m•v²/2 =
= 4000• 9² /2 = - 162000 J.
a =v² /2•s =9² /2• 0.5= 81 m/s²
F =ma =4000•81 = 324 000 N