A block attached to a spring oscillates in simple harmonic motion along the x axis. The limits of its motion are x = 10 cm and x = 50 cm and it goes from one of these extremes to the other in 0.25 s. Its amplitude and frequency are:
A) 40 cm, 2 Hz
B) 20 cm, 4 Hz
C) 40 cm, 1 Hz
D) 25 cm, 4 Hz
E) 20 cm, 2 Hz

Question

Quizplus · Accepted Answer

The amplitude is half the distance between the limits of motion, so it is (50-10)/2 = 20 cm.
The frequency is the inverse of the period, which can be found by T=2*(time to go from one extreme to the other) = 0.5 s. Therefore, frequency = 1/T = 1/0.5 = 2 Hz.
Thus, the correct choice is B.

A Block Attached to a Spring Oscillates in Simple Harmonic