What Speed Does the Roller Coaster Need to Maintain at the Top of a 14m Loop?

[yashi5166]

Homework Statement

A roller coaster is moving past the top of a loop of diameter 14m. The Normal force (directed downwards) provided by the track at the top of the loop is equal to one-half the weight of the car. What is the speed of the coaster car at this point?

Homework Equations

Only the diameter is given.

The Attempt at a Solution

Fc = Fg+Fn
→ mv²/r = mg + .5(mg)

and then minimum speed to go in a circle is sqrt(gr) but that won't work cause in order for that to happen Fn has to be 0 but here is half Fg. i believe the answer is 10.12m/s

 

[yashi5166]

Help ASAP

 

[PhanthomJay]

Your math is off a bit, and round it off to 10.1m/s

 

[yashi5166]

thanks soo much