Suppose you wish to whirl a pail full of water in a vertical circle at a constant speed without spilling any of its contents (even at the top of the circle!). If your arm is 0.65 m long (from shoulder to fist) and the distance from the handle to the surface of the water is 19.0 cm, what minimum speed is required?

V = 2.87 m/s

Explanation:

The minimum speed required would be that at which the acceleration due to gravity is negated by the centrifugal force on the water.

Thus, we simply need to set the centripetal acceleration equal to gravity and solve for the speed V using the following equation:

Centripetal acceleration = V^2 / r

where r is the distance of water from the pivot or shoulder.

For our case, r will be 0.65 + 0.19 = 0.84 m

and solving the above equation we get:

9.81 = V^2 / 0.84

V^2 = 8.2404

V = 2.87 m/s

a. is the answer because they are not shared