Q1. A stone has a mass of 5 x 10-4 kg and is wedged into the tread of an automobile tire, as drawing shows. The coefficient of static friction between the stone and each side of the tread channel is 0.7. While the tire surface is rotating at a maximum speed of 1 m/s, the stone flies out of the tread. The magnitude FN of the normal force that each side of the tread channel exerts on the stone is 1.8 N. suppose that only static friction supplies the centripetal force, and find out the radius r of tire.
Q2. A hot-air balloon is rising upward with the constant speed of 3.28 m/s. whilst the balloon is 8.48 m above the ground, the balloonist accidentally drops a compass over the side of the balloon. How much time elapses before compass hits the ground?