Chapter 8
1. (p.234 prob.12) A bicycle with 68-cm-diameter tires travels 7.0km. How many revolutions do the wheels make?
2. (p.235 prob.23) Pilots can be tested for the stresses of flying high-speed jets in a whirling "human centrifuge" which takes 1.0min to turn through 20 complete revolutions before reaching its final speed. (a) What was its angular acceleration (assume constant), and (b) what was its final speed in rpm?
3. (p.235 prob.26) A small rubber wheel is used to drive a large pottery wheel, and they are mounted so that their circular edges touch. If the small wheel has a radius of 2.0cm and accelerates at the rate of 7.2 rad/s2, and it is in contact with pottery wheel (radius 25.0cm) without slipping, calculate (a) the angular acceleration of the pottery wheel, and (b) the time it takes the pottery wheel to reach its required speed pf 65rpm.
4. (p.235 prob.31) Calculate the net torque about the axle of the wheel shown in Fig. 8-37. Assume that a friction torque of 0.40m.N opposes the motion.
5. (p.236 prob.38) A small 1.05-kg ball on the end of a light rod is rotated in a horizontal circle of radius 0.900m. Calculate (a) the moment of inertia of the system about the axis of rotation, and (b) the torque needed to keep the ball rotating at constant angular velocity if air resistance exerts a force of 0.0800N on the ball.
6. (p.236 prob.44) The forearm in Fig. 8-41 accelerates a 3.6-kg ball at 7.0m/s by means of the triceps muscle, as shown. Calculate (a) the torque needed, and (b) the force that must be exerted by the triceps muscle. Ignore the mass of the arm.
7. (p.237 prob.53) A merry-go-round has a mass of 1640kg and a radius of 8.20m. How much net work is required to accelerate it from rest to a rotation rate of one revolution in 8.00s? (Assume it is a solid cylinder.)