An accelerometer-a device to measure acceleration-can be as simple as a small pendulum. Suppose you are flying a small plane in a straight horizontal line and your accelerometer hangs 14.00° behind the vertical, opposite the direction of motion. What is your acceleration?

g tan (14°) = 2.44 m/s^2

Explanation:

If the pendulum is static, the tension will give us the magnitude of the acceleration of the plane.

Let T the tension of the pendulum and a the acceleration of the plane

The y-axis equation states that:

T cos (14) = mg

Similarly, for the x-axis

T sin (14) = ma

Dividing these equations we get

sin (14) / cos (15) = tan (15) = a/g

And solving for a:

a = g * tan (15)