# How Do I Know the Following Equations is Dimensionally Correct?

1. Jan 19, 2010

### JustSomeGuy80

1. The problem statement, all variables and given/known data
The problem asks to choose the dimensionally correct equation. In the back of the book it says that the correct answer is y=2 cm * cos(k*x), where k=2 m^-1. What do x and y stand for? The book doesn't say. Does each variable usually represent a certain dimension in physics? From my understanding, dimension y should be the same as dimension ( 2 cm * cos(k*x) ). But what is y?

2. Relevant equations

3. The attempt at a solution

2. Jan 19, 2010

### rock.freak667

If you had y=cosθ, cosθ is dimensionless but θ would be in radians. What should x be then?

3. Jan 19, 2010

### djeitnstine

Appears to be dealing with harmonics. Notably spring harmonics. If so 'y' would be vertical or horizontal displacement.

4. Jan 19, 2010

### JustSomeGuy80

an angle? arc length?

5. Jan 19, 2010

### rock.freak667

kx should give radians if k is m-1, x would be?