Can a pendulum measure the acceleration of your car?

Question

My friend and I are debating

Answer 1

Yes, if the pendulum is still before you accelerate, then you hit the gas, the pendulum will deflect. The deflection will be proportional to the force which is the pendulum's mass x acceleration, the same acceleration the car feels.

Answer 2

Certainly. If the pendulum indicates on an angle scale, then the acceleration of the car is g times the tangent of the angle of the pendulum, as measured from the vertical.

Answer 3

In principle yes, although it would be difficult. The period of a pendulum, that is, the number of seconds it takes to swing across and back again, equals 2 times pi times the square root of (L/a) where L= the length of the pendulum in metres and a is the vector sum of the acceleration due to gravity (9.81 metres/ sec/sec) and the acceleration of your car. So to work out the acceleration of the car you subtract the vector of g, which is vertically downwards. But an easier way would be to use a spring balance to measure the sideways acceleration. Here in NZ when you take your car in for its six-monthly warrant of fitness check, the accelerometer the mechanic uses to test the brakes works like a spring balance.

Answer 4

The car moves perpendicular to the motion of a pedulum, so I'm thinking no. However, maybe it could be used to estimate the acceleration of a rocket during takeoff.

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Yeh, the guys below me are right. I was thinking how the period of a pendulum already in motion would change if you increase the g's. However, if you start with a pendulum not in motion, the slant of the pendulum when you hit the gas could be used to measure the acceleration.