Question

Car 1 and Car 2 have an equal mass of 1,000 kg each. They were involved in a rear-end accident at a stop sign. here is what we know
1. car 1 approched the intersection from the top of a 25 meter hill
2.car 2 was on a flat stretch of road directly in front of car 1
3.at the bottom of the hill, Car 1 was going 20 m/s and Car 2 was going 30m/s before it stopped at the stop sign.
4.there were no sid marks left by car 2. Car 2 stopeed at the stop sign
5.After the acciedent, both cars were moving in the same direction 10m/s
6. we must push car 2 using 800 n of force, 10 meters off the road.

Answer 1

Thank you so much whoever that is going to help me. I'm doing this pratice worksheet. and I'm in honors biology, so I am totally not a physics person. ThankS!!!1

Answer 2

Wait, what do you want to find?

Answer 3

how much energy did car 1 lose from the top to the bottom of the hill. Thanks for coming!

Answer 4

okay-so first find the PE for it at the top of the hill. (assuming it was not moving)
PE=mgh
PE=1,000x9.8x25=245,000
Then find the KE at the bottom of the hill
KE=1/2 mv^2
KE=.5x1,000x(20^2)=200,000
Difference=245,000-200,000= 45,000 J #
My answer seems awfully large so you should check my work.

Answer 5

wait so its the difference? I thought is should be a sum?

Answer 6

i thought it was energy totaly=PE+KE?

Answer 7

It is the PE at the top and the KE at the bottom.

Answer 8

and it is assuming no initial movement

Answer 9

@Youngster : what abt the energy Car 1 loses during collision?

Answer 10

I can't seem to fix it in the calculation. there's also the case of point no. 6.
Work done in pushing Car2 = Force . displacement = 800 . 10 = 8000N
will this be the energy Car1 loses during collision?
If that's the case, then the answer would be
2,45,000 - 2,00,000 - 8000 = 37,000 J

Answer 11

@jokereq7 : do u know the final answer?