physics problem: accelerometer.

[lmf22]

A person dangles her watch from a string while the plane takes off. She notices that the string makes a angle of 25 degrees with respect to the vertical whie the plane accelerates to take off, which takes 19 seconds. What is the takeoff speed of the plane?

How do I get started? I think the X component is (Tension of String)*cos(25) and the Y component is (Tension of String)*sin(25)?
How do I find the accerleration with out knowing the mass of the watch?

[Doc Al]

How do I get started? I think the X component is (Tension of String)*cos(25) and the Y component is (Tension of String)*sin(25)?
Draw yourself a picture. I think you've got the components of the tension reversed. (The angle is with respect to the vertical.) Don't forget to consider all the forces on the watch.
How do I find the accerleration with out knowing the mass of the watch?
By applying Newton's 2nd law for the x and y components of the forces on the watch. (You'll find that the mass drops out.) Hint: the acceleration in the y-direction is zero.