Ch2

47.

a) V = Vi - gt, V = 0, t = 3, g = 9.8; hence Vi = 29.4 m/s.

b) y = 1/2*(V + Vi)*t = 44.1 m/s.

50.

a) At the top, V = 0, V = Vi - gt, t = 10, Vi = 98 m/s.

b) h = Vi*t - 1/2*g*t*t, t = 10, h = 490 m.

Ch3

31.

a) A+B = 2i-6j

b) A-B = 4i+2j

c)|A+B| = SQRT(2*2 + 6*6) = 6.32

d)|A-B| = 4.47

e)angle(|A+B|) = -71.6 = 288

f)angle(|A-B|) = 26.6

37.

a) F=F1+F2, F=120*cos(60)i+120*sin(60)j-80*cos(75)i+80*sin(75)j

F=(39.3i+181j)N, |F|=185N, angle = 77.8

b) F3 = -F = (-39.3i-181j)N.

51.

a) Rx = 40*cos(45)+30*cos(45) = 49.5

Ry = 40*sin(45)-30*sin(45)+20 = 27.1

R = (49.5i+27.1j).

b) |R| = 56.4, angle = 28.7.