Simple Harmonic Motion: Finding displacement at given time t

[Vanessa Avila]

Homework Statement

A 1.10 kg mass on a spring has displacement as a function of time given by the equation
x(t)=(7.40cm)cos[(4.16rad/s)t−2.42rad].

Find the position of the mass at t=1.00s;

Homework Equations

x = Acos(ωt+∅)

The Attempt at a Solution

I tried to just plug in the time t in that equation to solve for the displacement, but I'm getting 0.074 which apparently is not the right answer:

x = 0.0740m*cos(4.16rad/s(1.00s) - 2.42rad)
x = 0.074

 

[gneill]

Is your calculator's mode set for degrees or radians?

 

[Vanessa Avila]

aha! it's in degrees!

Is your calculator's mode set for degrees or radians?

 

[gneill]

aha! it's in degrees!

 

[Vanessa Avila]

Thanks a lot lol. I didn't catch that at all. I'm so stupid XD

 

[gneill]

Thanks a lot lol. I didn't catch that at all. I'm so stupid XD

Eh. It happens more often than you might think, and to some very clever people, too!