# Pendulum/Simple Harmonic Motion, what is its energy of motion?

by nicoleb14
Tags: pendulum, shm
 P: 11 A 1.2 kg mass attached to a spring oscillates with an amplitude of 5.1 cm and a frequency of 2.1 Hz. What is its energy of motion? I just have to use KE=1/2mv^2 right? do I have to involve the amplitude?
 P: 950 In SHM the KE is continually varying. So you are asking for the MAX KE, right?
 P: 11 I just need the energy of motion, so i guess that means KE max?
 P: 1,506 Pendulum/Simple Harmonic Motion, what is its energy of motion? The KE max will be the total energy of the motion. You are correct to use KE=1/2mv^2 but you need an expression for vmax in simple harmonic motion. You will need to find the spring constant (stiffness) and use this to find the max velocity. Do you know these equations?
 P: 950 What is the max linear velocity in SHM?
 P: 11 Vmax=Aw
 P: 950 Then you can find max ke = (1/2)mv^2 and use v = Aw
 P: 11 thank you sooo muuuch!!!!! :D
HW Helper
P: 2,318
 Quote by nicoleb14 A 1.2 kg mass attached to a spring oscillates with an amplitude of 5.1 cm and a frequency of 2.1 Hz. What is its energy of motion? I just have to use KE=1/2mv^2 right? do I have to involve the amplitude?
Is this mass hanging from the spring, or is this whole situation taking place horizontally??
 P: 11 the problem doesnt say
HW Helper
P: 2,318
 Quote by nicoleb14 the problem doesnt say
Assuming it is vertical, there is a constant interchange of elastic energy in the spring, gravitational potential energy and kinetic energy.

The total of them at any time will be constant.

That might be what is meant by the energy of the motion.

Even if the situation is horizontal [so no change in gravitational potential energy] there is a steady interchange between elastic potential energy and kinetic energy.

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