Answer:
d. 0.87 meters
Step-by-step explanation:
You want to know the length of a pendulum whose period is 1.87 seconds.
Period
The formula for the period of a pendulum in terms of its length is ...
T = 2π√(L/g)
Length
Solving for length, we have ...
T/(2π) = √(L/g) . . . . . . . divide by 2π
(T/(2π))² = L/g . . . . . . . square both sides
gT²/(4π²) = L . . . . . . . multiply by g
For the given period and value of g, we find the length to be ...
L = 9.81·(1.87/π)²/4 ≈ 0.87 . . . . meters
The length of the pendulum is about 0.87 meters.