Remember Newton's Second Law F = mass * acceleration
mass = 12 kg
acceleration = 4 m/s^2
F = 12 * 4 = 48 N
The object would have a centripetal acceleration <em>a</em> of
<em>a</em> = (12 m/s)² / (0.7 m) ≈ 205.714 m/s²
so that the required tension in the string would be
<em>T</em> = (0.5 kg) <em>a</em> ≈ 102.857 N ≈ 100 N
(rounding to 1 significant digit)
20waves/57.1s = 0.350 Hz
thank you!
