resolving a contact force into normal and frictional components?

Question

newtons craddle consists usually of 5 small steel spheres,each suspended by 2 light strings. modelling this by a number of particles each suspended by 2 strings inclinded at 80 degrees to the horizontal, find the tension in each string when:a) the weight of each steel sphere is 0.8 newtons b) the mass of each steel sphere is 0.1kg.

Answer 1

A FBD of the sphere shows that the horizontal forces balance

T1*cos(80)-T2*cos(80)=0
so the tensions are equal, call each T

The vertical forces
m*g-2*T*sin(80)=0
T=m*g/(2*sin(80))

a) m*g=0.8
T=0.41
b) m*g=0.1*9.8
T=0.50

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