Question

Hi a friend and I have a banked curve question that we would appreciate being walked through (; Detailed questiona nd diagram enclosed (;

Answer 1

1250 kg car rounds cruve with radius 72m banked at angle of 14 degrees. What amount of friction will be required and in what direction?

Answer 2

maybe forces in x and y directions first?

Answer 3

Sorry car is traveling 85 kph

Answer 4

Yah, forces in x and y first. Both x and y should equal 0 ^_^

Answer 5

I think were suppose to find how much centripital force needed and then how much natural force we have first?

Answer 6

The Normal force is what you find when you sum the forces in the y drection. The centripetal is then equal to amount of friction - those are both in the x.

Answer 7

ok

Answer 8

I was wondering......

Answer 9

I'm all astray. Let me compose myself for a sec :P

Answer 10

\[\sum fx= Ff - mgsin \theta - Fc\]

Answer 11

That's what I had though, but I'm wrong. That's with the x-axis pointing along the ramp, but centripetal acceleration points directly towards the center parallel to the ground.



there's a vertical and horizontal component of both the normal force and friction if we align our axis like we would on a normal non-ramp p[roblem.

Answer 12

I just found how to prove that this is not enough of an angle to not have friction so now need to find friction.

Answer 13

\[\sum F_x = N \sin\theta + \mu _s N \cos \theta = Fc\]

Answer 14

\[\sum F_y = - \mu _s N \sin \theta - mg + N \cos \theta = 0\]

Answer 15

it's weird :P

Answer 16

lol

Answer 17

Then you can solve for friction.

Answer 18

magic!

Answer 19

Does that make sense (minus the magic)?:

Answer 20

err, I guess when you saw that you needed friction was the velocity too great or too little?

Answer 21

My tutoring skillz are abysmal tonight :P

Answer 22

the velocity was to great, in order to to be frictionless we would need an angle of 38.3 degrees

Answer 23

Then yah, the friction would need to be pointing towards the bottom of the ramp (do you see why?), so those equations are right ^^