A roller coaster car (mass = M) is on a track that forms a circular loop (radius = r) in the vertical plane. If the car is to just maintain contact with the track at the top of the loop, what is the minimum value for its speed at that point?
(2rg)1/2.
rg.
(0.5rg)1/2.
(rg)1/2.
A coin of mass m rests on a turntable a distance r from the axis of rotation. The turntable rotates with a frequency of f. What is the minimum coefficient of static friction between the turntable and the coin if the coin is not to slip?
(4πfr2)/g.
(4πf2r)/g.
(4π2f2r)/g.
(4π2fr2)/g.
An object moves with a constant speed of 30 m/s on a circular track of radius 150 m. What is the acceleration of the object?
5.0 m/s².
0.17 m/s².
6.0 m/s².
Zero.
