What is the Frequency of This Simple Harmonic Motion?

[ryanuser]

Homework Statement

A body performaning simple harmonic motion has a displacement x given by the equation x= 30 sin 50t, where t is the time in seconds. what is the frequency of the oscillation?
Answers are:
A. 0.020Hz B. 0.13Hz C. 8.0Hz D. 30Hz E. 50Hz
(correct answer is B according to the mark scheme)

Homework Equations

ω = 2πf
x = Amplitude cos (2πf t)
x = Amplitude sin (2πf t)
x = Amplitude cos (ω t)
x = Amplitude cos (ω t)

The Attempt at a Solution

f = 50/2π = 7.9577Ηz according to the standard SHM formulas, which means the answer is C not B? what has gone wrong?

 

[Doc Al]

f = 50/2π = 7.9577Ηz according to the standard SHM formulas, which means the answer is C not B? what has gone wrong?

I'd say you are correct.

Interestingly, answer B is the inverse of that (1/f).

 

[Sahil Kukreja]

I'd say you are correct.

Interestingly, answer B is the inverse of that (1/f).

those who had calculated time period first and were in a hurry would mark (B) in the exam

 

[Doc Al]

those who had calculated time period first and were in a hurry would mark (B) in the exam

Exactly. It's a trap!