Three strings, in the horizontal plane, meet in a knot and are pulled with three forces such that the knot is held stationary. The tension in string 1 is T1 = 2.1 N. The angle between strings 1 and 2 is q12 = 130� and the angle between strings 1 and 3 is q13 = 120� with string 3 below string 1 as shown.
a) Find the tension in string 2.
T2 = N
b) Find the tension in string 3.
T3 = N
A mass of 1.1 kg is now placed on the knot and supported by a frictionless table in the plane of the strings. c) Find the acceleration of the mass if all the forces remain the same as above.
|a| = m/s2
d) If the sizes and directions of T2 and T3 remain the same, but T1 is increased by 2.4 N, what is the acceleration of the mass?
|a'| = m/s2
Physics Help -Three Pulling Strings - Please Quick?
The knot is held stationary =%26gt; T1 + T2 + T3 = 0(in vector)
=%26gt; Consider reference frame Oxy with: Ox - direction of string 1, Oy - perpendicular with string 1.
=%26gt; Ox: T1 - T2*cos50 - T3*cos60 = 0
Oy: T2* sin50 - T3 *sin60 = 0
=%26gt; T2 = T1/[(cot50 + cot60)*sin50] = 2.3N
T3 = T1/[(cot50 + cot60)*sin60] = 2.0N
All the forces remain the same =%26gt; net force is 0 =%26gt; a = 0
T2 and T3 remain the same, T1 increase be 2.4N =%26gt; net force F = 2.4N =%26gt; a = F/m = 2.2 m/s2
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