Question #1356

A visitor to a lighthouse wishes to determine
the height of the tower. She ties a spool
of thread to a small rock to make a simple
pendulum, which she hangs down the center
of a spiral staircase of the tower. The period
of oscillation is 10.8 s.
The acceleration of gravity is 9.8 m/s2 .
What is the height of the tower?
Answer in units of m.

Expert's answer

The formula for the period of oscillations can be written as

T = 2 π √(L/g)

L = gT^{2}/4 π^{2}

L = 9.8*10.8^{2} / 4π^{2} = 28.95 m.

T = 2 π √(L/g)

L = gT

L = 9.8*10.8

## Comments

Assignment Expert11.12.19, 16:29Dear D, this "center" means the space between the spiral stairs of the tower. So, you don't need to multiply the answer by two.

D.10.12.19, 19:28I thought since it says “center” maybe we should multiply the final answer by two, since center is half way through and they want the full height.

Thanks!

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