Harmonic motion: Y(t) = 4cos3nt

[1st_Golfer]

please help with this, am reading for fall class, ahead of time of course!
Y(t) = 4cos3nt

where n is pi

and t=.25
please just show me how, i am stuck

 

[pka]

What is the question?

Is this it: \(\displaystyle \L Y(t) = 4\cos \left( {3\pi t} \right)\quad \Rightarrow \quad Y\left( {\frac{1}{4}} \right) = 4\cos \left( {\frac{{3\pi }}{4}} \right)\)?

 

[1st_Golfer]

actually t stands for time in seconds and the time in this case is 0.25

 

[Deleted member 4993]

But....

What is the question?

 

[wjm11]

PKA has shown you everything you need to evaluate the expression. Just plug the values into your calculator and you will get -2(2)^.5 = -2.828 .

 

[1st_Golfer]

The displacement from an equilibrium of an oscilating mass attached to a spring is given by y(t) =4cos3n ( n represents pi) where y is measured in inches and t is measured in seconds. Find the displacement at the times as follows.

t= 0 .25 .5 .75 1.0 1.25
y= ? ? ? ? ? ?

[/i]

 

[Deleted member 4993]

Follow suggestion by pka (and wjm11) - show us your work if you need further help.

 

[Denis]

actually t stands for time in seconds and the time in this case is 0.25

1/4 = .25

 

[1st_Golfer]

vote of thanks

thank to pka, Denis, s.khan, and wjm11 for your effort, u made my day