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

Roller coaster

  • Thread starter ceday
  • Start date
11
0
1. Homework Statement
The normal force equals the magnitude of the gravitational force as a roller coaster car crosses the top of a 60m diameter loop-the-loop.



2. Homework Equations
What is the car's speed at the top?


3. The Attempt at a Solution
hello, this problem doesn't give much information
would normal force be pointing down?

so Fnet= ma=mv^2/r but its doesnt give those variables

can anyone help?
thanks :)
 

LowlyPion

Homework Helper
3,079
4
Don't you have all you need?

Draw a diagram.

m*g down and mv2/r up

But it says the Normal force is still m*g

If the net force must be m*g and you have m*g acting down against the centripetal force, what must the centripetal force be?
 
11
0
Is the net force in the y direction zero?

does the centripetal force = 2mg since normal and gravity both point downward?

im lost since this coaster is upside down
 

LowlyPion

Homework Helper
3,079
4
Is the net force in the y direction zero?

does the centripetal force = 2mg since normal and gravity both point downward?

im lost since this coaster is upside down
Not lost at all.

The centripetal force is 2*m*g.
 
11
0
so would net force in the y direction = zero?

if it is zero, i dont think it would be solvable because we dont know the mass

wouldnt it be 0=mv2/r
 
11
0
ok, i got the answer but i used the net force=2mg
i still dont understand why this is so
 

LowlyPion

Homework Helper
3,079
4
ok, i got the answer but i used the net force=2mg
i still dont understand why this is so
FNormal = ∑ F = Fcentrip - Fgravity

m*g = m*v2/r - m*g

2*m*g = m*v2/r
 

Related Threads for: Roller coaster

  • Posted
Replies
1
Views
4K
  • Posted
Replies
2
Views
5K
  • Posted
Replies
1
Views
2K
  • Posted
Replies
2
Views
4K
  • Posted
Replies
1
Views
6K

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