One more comedy mistake

Ah go on, here’s one more

Clearly whoever wrote this question wanted the student to use a=-ω²x, and convert f into ω, but look at the numbers closely… what is the length of that pendulum? It’s less than 1cm. How can a pendulum less than 1cm long be displaced from equilibrium by 20cm? Oh dear.

I think I need to make a new blog category for physics mistakes!