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1. The problem statement, all variables and given/known data

A block slides on the frictionless loop the lopp track shown in this img, what is the min height at which it can start from rest and still make it around the loop

3. The attempt at a solution

I haev solved this problem TWO ways, and i cant decide which way is correct

the eqn...

U0+K0 = K+U

where U = potential energy and K = kinetic energy

first

m * g * h + (1/2) * m * v^2 >= m * g * 2 * R

final answer =h = 2R

the way my friend set it up and solved it

m * g * h >= (1/2) * m * v^2 + m * g * 2 * R

my friend solved it this way and goth = (5*R) / 2

but i cant seem to get what he got and i geth=h-2r+2rwhich says the min height has to be the min height of the radius aka h = 2R

any hints, tips, or advice?

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# Homework Help: Loop the Loop and block

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