A roller coaster starts from A, 120m above the ground, as shown. Assume no friction from the wheels and air, and that no energy is lost to heat, sound, and so on. The radius of the loop is 40m.

Options

A. The roller coaster cannot loop the loop
B. The speed of the roller coaster at point D is nearly 28.2 m/s
C. The speed of the roller coaster at point B is twice the speed at point F.
D. The speed of roller coaster at point H is zero.

Explanation

For looping loop
`v_(c)gtsqrt(5gr)=sqrt(5xx10xx40)=20sqrt(5)`
`v_(c)=sqrt(2xxgxx120)gtsqrt(5gr)`
`v_(D)=sqrt(2g(120-80))=20sqrt(2)=28.2m//s`
`v_(B)=sqrt(2gxx60)`
`v_(F)=sqrt(2gxx120)`