This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: September 19, 2007 PHY2053 Quiz 3 (Section 4.1-4.5) Name: UFID: 1. (5 pts) Two people are holding a mass of 20kg with two strings attached to it. One person pulls one of the strings with a force of 120N at an angle of 50 to the horizontal. Find the direction of the force the other person exerts on the other string. Express three forces in components (we take right as +x and up as +y): Fg = (0, -20 9.8) = (0, -196) T1 = (120cos50, 120sin50) = (77.1, 91.9) T2 = (Tx, Ty) Since Fg+T1+T2=0, we get 0+77.1+Tx = 0, Tx = -77.1-196+91.9+Ty = 0, Ty = 104.1 = tan (104.1/-77.1)+180 = 126.5 Opposite side to the first person and 53.5 to the horizontal. 2. (5 pts) Two crates of masses 20kg and 30kg are connected by a light string that passes over a frictionless pulley. The 20kg crate lies on a smooth incline of angle 60 passes over a frictionless pulley....
View Full Document