Physicsbobpursley please check
posted by Joey .
This is the question I posted about two hours ago and I worked it out two wayscould you scroll down and check it, please?If I have a roller coaster, and hill 1 height is 50cm and hill height 2 is 25 cm and the PE is .9 as it approaches the top of hill 2, how do I calculate the speed. PE first hill was 18
Please help
PhysicsPlease help  bobpursley, Thursday, November 4, 2010 at 5:52pm
THe PE is .9 where? Where did the coaster start?
PhysicsPlease help  Joey, Thursday, November 4, 2010 at 5:54pm
The coaster started at .18PEthe .9 is the PE at the top of the second hill.The second hill is lower.
PhysicsPlease help  bobpursley, Thursday, November 4, 2010 at 6:01pm
Well, the difference in the two Potential energies is now KEnergy, 1/2 mv^2, solve for v.
PhysicsPlease check  Joey, Thursday, November 4, 2010 at 6:21pm
. The way to calculate this is you take the KE would be .9. You would say .9 = ½ (.035 x v^2) = 2.215. Correct or no?
PhysicsPlease check  Joey, Thursday, November 4, 2010 at 7:31pm
Should I have done this as 1/2mv^2 = mgh
Cross out like terms and get to v^2 = square root of 2 x g x .25m(h)= 2.125 m/s
Would this be correct?

First, you have so many math errors it hurts.
If 1/2 mv^2=.9J
then v^2=2*.9/.035
v=7.17m/s I have no idea where you got 2.215m/s
You have told me several things about the initial PE
a) it was a height of .5m (PE= .035*9.8*.5 = .17J ( you indicated in your solution mass was .035kg, I am not certain where that came from)
b) it was 18J
c) it was .9J at a hill half the height.
So I don't know if it is right or not, I do not know the initial PE.
KE on topsecond hill= InitialPEPEtopsecondhill
That is the principle you use here. 
You second solution makes no sense. Why would you set the KE of an object equal to its PE?
Respond to this Question
Similar Questions

8th Grade Algebra1
I don't understand this question, so if anyone can answer it, that would be great! We are doing motion problems, so as you probably know, the formula is d=rt. (distance equals rate times time.) We have to make a chart to answer the … 
Physics
Another question :) At the top of its drop hill, a 1,000 kg roller coaster has 200,000 J of total energy. If the top of the next hill is 13 meters, what is the kinetic energy of the roller coaster on this hill? 
PhysicsPlease help
If I have a roller coaster, and hill 1 height is 50cm and hill height 2 is 25 cm and the PE is .9 as it approaches the top of hill 2, how do I calculate the speed. Please help 
Physicsbobpursleyplease check
This is the question I posted about two hours ago and I worked it out two wayscould you scroll down and check it, please? 
physics
4. An 800.0 kg roller coaster car is at rest at the top of a 95 m hill. It rolls down the first drop to a height of 31 m. When it travels to the top of the second hill, it is moving at 28 m/s. It then rolls down the second hill until … 
phycis
A roller coaster has two hills and starts from rest atop the first hill , which is the higher of the two hills . The secound hill increases if the height of the initial hill is increased by 20m 
physics
If the roller coaster track has a hill at the end that was equal in height to the original hill, would the marble make it all the way to the top? 
PHYSICS
An 800.0 kg roller coaster car is at rest at the top of a 95 m hill. It rolls down the first drop to a height of 31 m. When it travels to the top of the second hill, it is moving at 28 m/s. It then rolls down the second hill until … 
physics
A 10,000N car is on a roller coaster. at the top of the tallest hill (position 1) the reaches a hieght 36m above the lowest point on the roller coaster (position 2). after accelerating down the hill the roller coaster makes another … 
Algebra
I NEED HELP A$AP, PLEASE! I don't understand how to do this :( I have to draw a short roller coaster on graph paper Directions: 1. Draw the side view of your roller coaster on graph paper. For the sake of simplicity, assume that your …