- #1
ace123
- 250
- 0
A 920-kg sports car collides into a rear end of a 2300 kg SUV stopped at a red light. The bumpers lock, the brakes are locked, and the two cars skid foward 2.8 m before stopping. The police officer, knowing that the coefficient of kinetic friction between tires and road is .80 , calculates the speed of the sports car at impact. What was that speed?
This is all that I did before I got stuck.
I set up the conservation of momentum :920 kg * V[tex]_{1}[/tex]= 3220 * V[tex]_2{}[/tex]
Then I did F[tex]\Delta[/tex]t= [tex]\Delta[/tex]P
I found the force to be 25244= 3220 V[tex]_{2}[/tex] / [tex]\Delta[/tex]t
Now is where I get stuck. I think I did something wrong because I'm pretty sure I need to do v/t =d.
Also not sure if I should use kinetic energy in this one since it's not conserved.
Any help will be great. Thanks as always.
On a side note: Isn't it hilarious how the officer knows the kinetic friction and calculates the speed.
This is all that I did before I got stuck.
I set up the conservation of momentum :920 kg * V[tex]_{1}[/tex]= 3220 * V[tex]_2{}[/tex]
Then I did F[tex]\Delta[/tex]t= [tex]\Delta[/tex]P
I found the force to be 25244= 3220 V[tex]_{2}[/tex] / [tex]\Delta[/tex]t
Now is where I get stuck. I think I did something wrong because I'm pretty sure I need to do v/t =d.
Also not sure if I should use kinetic energy in this one since it's not conserved.
Any help will be great. Thanks as always.
On a side note: Isn't it hilarious how the officer knows the kinetic friction and calculates the speed.