Speed of the roller coaster at the top of the loop= 7.67 m/s
Explanation:
using the law of conservation of energy
KEi + PEi= KEf + PEf
KEi= kinetic energy at the top of the hill=0 because the car is at rest there.
PEi= potential energy at the top of the hill
PEf= potential energy at the top of the loop
KEf= kinetic energy at the top of the loop
Also kinetic energy= 1/ 2m v² and potential energy= mgh
m= mass
h= height
v= velocity
so 0+ mghi = 1/2mv² + mg h
500 (9.8)(10)+ 1/2 (500) v²= 500 ( 9.8) (7)
49000+250 v²= 34300
250v²= 14700
v²=58.8
v=7.67 m/s