- #1
Victoria_235
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Homework Statement
Here is the problem.
A small ball of mass m moves without friction attached to a cwire.
The ball moves under the action of gravity and a spring of constant k whose other end is fixed in the point A, with OA = R / 2.
The spring is tension free when the spring is R/2
to. Calculate the potential energy of the mobile as a function of the angle φ.
B. Calculate the speed at which the mobile must be released in position with free tension of the spring so that the ball can go around.
The system is on the horizontal plane.
Solve also in case it is in the vertical plane.
Homework Equations
The Attempt at a Solution
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So, I have been trying to solve it...
Firstly, I have considered Newton's equations.
On k direction, perpendicular to the problem plane, is gravity, g and the reaction force of the wire, as the ball is moving in OXY plane, the resultant should be 0.
N_k - m*g = 0
On the other hand, we have the OXY forces.
F_s (spring force) and the reaction of the wire in the radial direction (N_r)
so:
F_s + N_r = m*a, where m is the ball mass, and a is the aceleration
The energy balance, I think is this way:
Kinetic energy -> K_e = 1/2m(v_i)², where v_i is the initial speed.
Potential energy -> If I consider the system in the horizontal plane with 0 high, it should be 0.
Spring energy -> S_e= 1/2k*x^2, where x is the distance to any point in the wire to A.
But I have no idea to continue it...
Could anybody help me? :)