Chap 6 EXAMPLE #1 Problem #30, page 179 In an electricity experiment, a 1.0-g plastic ball is suspended on a 60-cm-long string and given an electric charge. A charged rod brought near the ball exerts a horizontal electric force, Felec , on it, causing the ball to swing out to a 20°angle and remain there.

(a) What is the magnitude of Felec? (b) What is the tension in the string? Chap 6 EXAMPLE #2 Problem #12, page 178 What thrust does a 200-g model rocket need in order to have a vertical acceleration of 10 m/s2 (a) On Earth? (b) On the moon, where g = 1.62 m/s2? Chap 6 EXAMPLE #3 Problem #18, page 178 A stubborn, 120-kg mule sits down and refuses to move. The drag the mule to the barn, the farmer ties a rope around the mule and pulls with his maximum force of 800 N. The coefficients of friction between the mule and the ground are µs = 0.8 and µk = 0.5. Is the farmer able to move the mule? Chap 6 EXAMPLE #4 Problem #42, page 180 Sam, whose mass is 75 kg, takes off down a 50-m-high, 10° slope on his jet-powered skis. The skis have a thrust of 200 N. Sam’s speed at the bottom is 40 m/s. What is the coefficient of kinetic friction between his skis and the snow?