The systems shown above are in equilibrium with m = 9.40 kg and = 25.0°. If the
ID: 1961023 • Letter: T
Question
The systems shown above are in equilibrium with m = 9.40 kg and = 25.0°. If the spring scales are calibrated in newtons, what do they read? Ignore the masses of the pulleys and strings and assume the pulleys and the incline are frictionless.
Scale in (a) = _______ N
I am only having trouble figuring the answer to part A, i thought it would be 0 N since it is balanced on either side, but this is not the correct answer.
I also tried 2*mg = 2*9.4*9.8 = 184.2, but this is not the correct answer either..
Explanation / Answer
Starting from the left, the ball of mass m = 9.4 kg has two forces acting on it: gravity Fg = mg and tension T1.
Summing forces in the upwards direction we have
= ma = 0
Moving on to the scale, we see that the scale has two forces on it: tension from the left ball T1 and tension from the right
ball T2. Summing the forces in the rightwards direction we have
F = T2 T1
= ma = 0
Following exactly the same reasoning we applied to the left ball.