A grinning oddball of mass m stands a distance d from the bottom of a stationary ladder having mass M and length L, as in the figure. What is the magnitude of the friction force that the floor exerts on the ladder? Assume the wall is frictionless and 58 kg, M = 22 kg, L = 3.1 m, let m d = 1.3 m, and D = 1.2 m. d L m M ·D→ fs = N

Jamal and Dayo are lifting a large chest, weighing 207 lb, by using the two rope handles attached to either side. As they lift and hold it up so that it is motionless, each handle makes a different angle with respect to the vertical side of the chest (Fig. P5.76). If the angle between Jamals handle and the vertical side is 25.0 and the angle between Dayos handle and the vertical side of the chest is 30.0, what are the tensions in each handle? FIGURE P5.76

A person places a bathroom scale in the center of the floor and stands on the scale with his arms at his sides ( Fig. 3.26a). If he keeps his arms rigid and quickly raises them over his head (Fig. 3.26b), he notices the scale reading increases as he brings his arms upward. Why? Then, with his arms over his head (Fig. 3.26c), he quickly lowers his arms to his side. How does the scale reading change and why? (Try it yourself.)

Consider the disk in Problem 71. The disks outer rim hasradius R = 4.20 m, and F1 = 10.5 N. Find the magnitude ofeach torque exerted around the center of the disk. FIGURE P12.71 Problems 71-75

Find the net torque on the wheel in Figure P10.23 about the axle through O, taking a = 10.0 cm and b = 25.0 cm. Figure P10.23

A crane of mass m1 = 3 000 kg supports a load of mass m2 = 10 000 kg as shown in Figure P10.36. The crane is pivoted with a frictionless pin at A and rests against a smooth support at B. Find the reaction forces at (a) point A and (b) point B. Figure P10.36

A 20.0-kg horizontal plank 4.00 in long rests on two supports, one at the left end and a second 1.00 m from the right end. What is the magnitude of the force exerted on the plank by the support near the right end? (a) 32.0 N (b) 45.2 N (c) 112 N (d) 131 N (e) 98.2 N

Check Your Understanding The U.S. Air Force uses “10gs” (an acceleration equal to 109.8m/s2 ) as the maximum acceleration a human can withstand (but only tot several seconds) aid survive. How much time must the Enterprise spend accelerating if the humans on board are to experience an average at most 10gs of acceleration? (Assume the inertial dampeners are offline.)

Repeat the preceding problem replacing the marble with a solid cylinder. Explain the new result.

A 20.0-kg horizontal plank 4.00 m long rests on two supports, one at the left end and a second 1.00 m from the right end. What is the magnitude of the force exerted on the plank by the support near the right end? (a) 32.0 N (b) 45.2 N (c) 112 N (d) 131 N (e) 98.2 N