Simple harmonic motion A level physics help?

Hi. Please attempt this question and let me know what answer you get. I keep getting B) 0.8ms^-1 but the correct answer is A.

Please post method working if you manage to get A.

Thank you

The speed equation for simple harmoic motion is given by; omega x the square root of the amplitude squared - the displacement squared.

Omega can be calculated because omega = 2pi x frequency, which because f = 1 / T, can be written as omega = 2pi / T.

Also, we have to change units to metres, therefore 10 cm and 6 cm become 0.10 metres and 0.06 metres, respectively.

Plugging these back into the speed equation, we are left with, speed = (2pi / 0.8) x the square root of (0.10)^2 - (0.06)^2, which will give you 0.6283185307 ms-1.

Rounding this off, we are left with 0.6 ms-1, which is A.

Vmax = 2pi x f x A is just for calculating the maximum speed of the object, without reference to any specific point in an oscillation.

Whereas, by using V = Omega x the square root of Amplitude squared - Displacement squared, you can calculate the velocity of the object at any given point in it's oscillation.

http://physicsnet.co.uk/a-level-physics-as-a2/further-mechanics/simple-harmonic-motion-shm/ you might find this page helpful.