• Support PF! Buy your school textbooks, materials and every day products via PF Here!

Another roller coaster question

  • Thread starter vorcil
  • Start date
391
0
http://img13.imageshack.us/img13/9297/masteringphysicsq1.jpg [Broken]

At the bottom it's 510N, Top 666N,

at bottom Fnormal=netforce= mv^2/r + mg

http://img13.imageshack.us/img13/8244/masteringphysicsq1g.jpg [Broken]
-my attempt

I'm not sure how to figure out the acceleration
or determine the time for one loop on the graph.
 
Last edited by a moderator:
391
0
great 510 n = 5 seconds....
666n = 15 seconds
 

LowlyPion

Homework Helper
3,079
4
I don't think you need to determine the period or the velocity.

Where will the weight be the minimum? And the maximum?

Presuming that the ferris wheel is not a super spinning Whirl-a-Gig, then you know

mg - mv2/r = Min
mg + mv2/r = Max

Then just solve for m*g.
 
391
0
I don't think you need to determine the period or the velocity.

Where will the weight be the minimum? And the maximum?

Presuming that the ferris wheel is not a super spinning Whirl-a-Gig, then you know

mg - mv2/r = Min
mg + mv2/r = Max

Then just solve for m*g.
I got two different awnsers, for the coaster at the bottom 12.171kg and top 14.52kg
i think i've done it wrong :\
 

LowlyPion

Homework Helper
3,079
4
I got two different awnsers, for the coaster at the bottom 12.171kg and top 14.52kg
i think i've done it wrong :\
Try constructing the equations.

Then subtract 1 from the other.

You will determine then what mv2/r is and then you can figure the weight from either of the 2 equations.

I only get 1 answer.
 
391
0
Try constructing the equations.

Then subtract 1 from the other.

You will determine then what mv2/r is and then you can figure the weight from either of the 2 equations.

I only get 1 answer.
What like?
666-510 = (mg + mv^2/r) - (mg - mv^2/r)
i can't figure out the velocity for the mv^2/r
 
391
0
666 = mg + mv^2/r
510 = mg - mv^2/r

666+510 = 2mg + - mv^2/4
= 1176 = 2mg
1176/9.8 = 120
120/2 = 60

60kg?
 

LowlyPion

Homework Helper
3,079
4
666 = mg + mv^2/r
510 = mg - mv^2/r

666+510 = 2mg + - mv^2/4
= 1176 = 2mg
1176/9.8 = 120
120/2 = 60

60kg?
That's right. Adding them works too. In fact better as it yields the m*g directly.

m = 1176/(2*9.8) = 60
 

Related Threads for: Another roller coaster question

  • Posted
Replies
1
Views
6K
  • Posted
Replies
1
Views
2K
Replies
4
Views
848
  • Posted
Replies
9
Views
2K
  • Posted
Replies
3
Views
641

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top