# Finding Amplitude

## Homework Statement

An air-track glider attached to a spring oscillates between the 9.23 cm mark and the 50.23 cm mark on the track. The glider completes 27 oscillations in 44.7 s. angular frequency of the glider? (in rad/s)
3.7933
what is the amplitude of the glider?

x=Acos(wt+ro)

## The Attempt at a Solution

I considered that at x=9.23 the amplitude was zero and so is ro.
Hence, x=50.23 would equal just 50.23 cm=Acos(3.79(44.7)). But A turned out to be negative. What am I doing wrong? How do I solve this problem? Thank you in advance.

dx
Homework Helper
Gold Member
What is the center of oscillation here? The amplitude is the maximum distance from the center that the glider reaches.

Would it be half the distance the glider travels which is 20.5 cm?

dx
Homework Helper
Gold Member
Correct.

It still gives me a negative number if I do .205/((cos(3.79*44.7)).

dx
Homework Helper
Gold Member
Negative number for what?

For the amplitude A.

dx
Homework Helper
Gold Member
You just said the amplitude was 20.5 cm, which is correct.

OH! Ok I get it. Thank you very much.