Group+A+Period+6

Welcome Group A!! You are to complete problems 1, 7 and 13 from Section 4.6 on this page. Feel free to use the discussion forum to bounce ideas off each other. Each member of the group should contribute!!

Problem 1

Original Equation: A = pi (r^2) dA/dt = pi (2r (dr/dt)) + 0

Answer: dA/dt = 2pi(r)(dr/dt)

Problem 7

Original Equation: V = IR Given:V is increasing at the rate of 1 volt/sec; I is decreasing at the rate of 1/3 amp/sec. t = time.

a) dV/dt = 1 volt/sec

b) dI/dt = -1/3 amp/sec

c) dV/dt = I (dR/dt) + R (dI/dt)

d) V = 12 volts; I = 2 amps 12 volts = 2 amps x (R) R = 6 ohms 1 volt/sec = 2 amps (dR/dt) + 6 ohms (-1/3 amp/sec) 3 volt/sec = 2 amps (dR/dt) dR/dt = 3/2 ohms/sec

Answer: 3/2 ohms/sec = dR/dt (R is increasing since dR/dt is positive)

Problem 13

-Pythagorean Theorem S=10, X= (51)^(1/2) (7^2) + (x^2) = (s^2) 49 + (x^2) = (s^2) 2x(dx/dt) = 2s(ds/dt) x(dx/dt) = s(ds/dt)

(51)^(1/2) (dx/dt) = 10(300) (dx/dt) = 420.08 mph