V. Does kinetic friction depend on area of contact? 15. Make a prediction. If the area of contact increases, does the kinetic friction increase, decrease or stay the same? Give a reason for your prediction.

x Incorrect The force P is applied to the 30-kg block when it is at rest. Determine the magnitude and direction of the friction force exerted by the surface on the block if (a) P = 0, (b) P = 85 N, and (c) P = 131 N. (d) What value of P is required to initiate motion up the incline? The static and kinetic coefficients of friction between the block and the incline are us = 0.18 and µk = 0.12, respectively. The friction force is positive if up the incline, negative if down the incline. %3D P 30 kg 18° H, = 0.18 H = 0.12 12 Answers: (а) F 3D N (b) F (c) F = (d) P =

What is the terminal speed of a 7.11 kg spherical ball that has a radius of 1.69 cm and a drag coefficient of 1.38? The density of the air through which the ball falls is 1.20 kg/m³. Number i Units

A uniform wire with mass M and length L is bent into a semicircle. Part A Find the magnitude of the gravitational force this wire exerts on a point with mass m placed at the center of curvature of the semicircle. Express your answer in terms of G, M, m, L, and T. F =