# need help answering physics question

Hi

I attempted the question and got the wrong answer

A Block Of Mass M Is Undergoing SHM On A Horizontal, Frictionless Surface While It Is Attached To A Light, Horizontal Spring That Has Force Constant K. The Amplitude Of The SHM Of The Block Is A. What Is The Distance |X| Of The Block From Its Equilibrium Position When Its Speed V Is Half Its Maximum Speed Vmax? Express In Terms Of A Is This Distance Larger
A block of mass m is undergoing SHM on a horizontal, frictionless surface while it is attached to a light, horizontal spring that has force constant k. The amplitude of the SHM of the block is A.

What is the distance |x| of the block from its equilibrium position when its speed v is half its maximum speed vmax? Express in terms of A

Is this distance larger or smaller than A/2?

I started by setting ek=ep
then I substituted for vmax into Ek
I isolated for x and got a/2 not sqrt3/2

what is the right way to go about this question?
Original post by billybob1111

I started by setting ek=ep
then I substituted for vmax into Ek
I isolated for x and got a/2 not sqrt3/2

what is the right way to go about this question?

There's no reason to set kinetic energy equal to potential energy. That's what you'd do if you were trying to find the maximum extension for a given $v_{max}$, or the maximum speed.

When the block is at $\frac12 v_{max}$, it has both kinetic and potential energy
Original post by Sinnoh
There's no reason to set kinetic energy equal to potential energy. That's what you'd do if you were trying to find the maximum extension for a given $v_{max}$, or the maximum speed.

When the block is at $\frac12 v_{max}$, it has both kinetic and potential energy

ah okay so its
Ek+Ep= Et?
Original post by billybob1111
ah okay so its
Ek+Ep= Et?

If Et is the maximum kinetic or potential energy it has at some point, yes