- #1
anewera
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Homework Statement
A high school buddy exerts a horizontal force on a swing that is suspended by a rope that is 5.0 meters long, holding at an angle of 30 degrees with the vertical. The child in the swing has a mass of 30kg and dimensions that are negligible compared to the length of the swing. The mass of the rope and the seat are negligible.
a) What are the forces acting on the child?
b) Calculate the tension in the rope, in Newtons.
c) Calculate the horizontal force exerted by the high school buddy in N
The buddy now releases the swing from rest
d) Calculate the tension in the rope just after the release (the swing is instantaneously at rest) in N.
e) Calculate the tension in the rope as the swing passes through its lowest point in N.
Homework Equations
T = (m * v^2 / r) + mg
F = ma
The Attempt at a Solution
a) Well there's no friction and since it's stationary, I don't think there should be a centripetal force but there's Weight...and a Normal force?
b)I was thinking T = mg cos(theta) but then I realized it's not just the rope that is supporting all the weight of the child. The buddy is keeping the swing from moving forward...so that throws me off.
c) I really don't know how to do this, mg would only make sense if there was just a downward vector so now I'm confused.
d) So now that the child isn't holding it I'm guessing the tension is mg cos (theta).
e) T = (m * v^2 / r) + mg, plug in and solve should work?
Thanks in advance...more than half the other class failed the test for rotational motion and I really want to know how to do these harder questions...