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## Homework Statement

Granted, I may be thinking too much into this.

You are sitting in a jet airplane as it accelerates at a constant rate down the

runway. Being a good physics student you hold the string of a small pendulum of length

l = 0.75m and mass m = 1 kg. You then measure the angle between the string and a

vertical line and [itex]\theta = 37^{\circ}[/itex]. Assume [itex]\sin\ 37 = 3/5; \cos\37 = 4/5; \tan\ 37 = 3/4[/itex], and take [itex]g = 10 m/s^2[/itex]

a.) What is the magnitude of the acceleration of the plane?

b.) What is the tension on the string?

## Homework Equations

Nonrelativistic coordinate transformation: [itex]x' = x - vt[/itex]

## The Attempt at a Solution

There are a couple of ways I can see doing this, but I think both show that I don't completely understand what's going on. My first thought was that the net acceleration is zero, meaning that [itex]a = g\cos\theta = 8 m/s^2[/itex]. This would make the tension [itex]\sqrt{m^2g^2 + mg^2\cos^2\theta} = \sqrt{100 + 100.5625} = \sqrt{200.5625}[/itex] but I don't think that's correct.

Alternatively, it could involve circular motion, although I have no idea what to plug in for the velocity in the centripetal force equation.

Thanks for the help!