Q. The boy in the figure here is initially seated on the top of a hemispherical ice mound of radius R = 13.6 m. He begins to slide down the ice, with a negligible initial speed.
Approximate the ice as being frictionless. At what height does the boy lose contact with the ice?
Q. A stationary bicycle is raised off the ground, and its front wheel (m = 1.3 kg) is rotating at an angular velocity of 12.1 rad/s (see the drawing). The front brake is then applied for 3.0 s, and the wheel slows down to 2.8 rad/s. Assume that all the mass of the wheel is concentrated in the rim, the radius of which is 0.33 m. The coefficient of kinetic friction between each brake pad and the rim is μk = 0.85. What is the magnitude of the normal force that each brake pad applies to the rim?