Question

A roller coaster designer is constructing a track with a goal that the riders will feel weightless when they reach the top of a bunny hill that is $45m$ high.
Which of the following best represents the velocity that the designer should construct the track for the car to reach the top of the hill if it can be assumed that the coaster car is at the top of a vertical circle at this position?

• A. $15.0m/s$
• B. $21.0m/s$
• C. $30.0m/s$
• D. $220m/s$
• E. $441m/s$

Answer 1

Answer: (B)

$21.0m/s$

Since the person feels weightlessness at top, the centripetal force would balance the weight of object at that point.

Hence $m\frac{v^2}{R}=mg$

$⟹v=\sqrt{gR}\approx 21m/s$