pendulum problem?

Question

A simple pendulum, consists of an object suspended by a string. The object is assumed to be a particle. The string, with its top end fixed, has negligible mass and does not stretch. In the absence of air friction, the system oscillates by swinging back and forth in a vertical plane. If the string is 1.60 m long and makes an initial angle of 34.5° with the vertical, calculate the speed of the particle at the following positions.
(a) at the lowest point in its trajectory
m/s
(b) when the angle is 15.0°
m/s

Answer 1

You don't need the mass. Both PE and KE are proportional to mass so it cancels out.
PEinit/m = gh = g*1.6*(1-cos(34.5 deg))
KE/m = v^2/2, so
A. At h=0, KE/m = PEinit/m; v = sqrt(2KE/m)
B. At 15 deg, PE/m = gh = g*1.6*(1-cos(10 deg))
KE/m = (PEinit-PE)/m = g*1.6*(1-cos(34.5 deg) - 1-cos(10 deg))
v = sqrt(2KE/m)

Answer 2

For small plenty, the formulation during a pendulum is: T = 2* pi * sqrt (L/g) Divide the size of the rope with the aid of the gravitational acceleration (9.8 m/sec^2), take the sq. root, and multiply with the aid of two pi. aside from this reason, you already understand the era and don't understand the size. Rearrange the equation to sparkling up for L T/(2 pi) = sqrt (L/g) T^2/(4 pi^2) = L/g gT^2/(4 pi^2) = L

Answer 3

Not enough information. You need the mass of the pendulum to figure the potential energy at height and kinetic energy at the lowest point. From there you can use a little algebra to figure out the velocity from E=mv^2.