Simple harmonic motion acceleration

[pyman999]

Homework Statement

Homework Equations

acceleration = -(2*pi*f)^2 * x, where f is the frequency and x is the displacement from equilibrium.

The Attempt at a Solution

I thought the acceleration would be greatest when the displacement from equilibrium is greatest, so at point P, but the answer is at point R and I'm not sure why.

 

[BvU]

Re relevant equation: since there is damping, the expression for the acceleration is a little different: generally the damping force is taken to be proportional to the speed, so there is a term in the force $-\beta v$ and we write $$ m a + \beta v + k x = 0 $$ so that $$a = -{\beta \over m} v - {k\over m} x$$

Re where magnitude of a is maximum: I agree with you. Both at P and R |v| = 0 and |x| is bigger at P.

 

[pyman999]

Re relevant equation: since there is damping, the expression for the acceleration is a little different: generally the damping force is taken to be proportional to the speed, so there is a term in the force $-\beta v$ and we write $$ m a + \beta v + k x = 0 $$ so that $$a = -{\beta \over m} v - {k\over m} x$$

Re where magnitude of a is maximum: I agree with you. Both at P and R |v| = 0 and |x| is bigger at P.

I'm fairly sure the answers I have been given for this question are wrong then, as I'm also getting weird results for later parts, thanks.