Question

For the next part, you will need to know that the position d of an object attached to a spring that oscillates with period T=1.0s is a sinusoidal function of time: d=kcos(2πt)d=kcos(2πt) for some constant k.

Assume that the initial position of the object is d0=2.0cm. Find the following positions of the object: d1 at t1=0.25s , d2 at t2=0.50s , d3 at t3=0.75s, and d4 at t4=1.0s.

so I found out k=2cm. I plug everything in and got 1.999, 1.997, 1.993, and 1.988.
masteringphysics says im still wrong?
Help please!

Answer 1

By looking at the sinusoidal wave graphed out, the period is T=1.0s. Which means in one second the d will be the same as the beginning. So we know that d0=2.0cm so d4 at 1.0s = d0 or 2cm. Then we know that half of that period would be the negative of the intial or d2 at .5s= -2.0cm. Finally the remaining times are half of that which will make them rest on the axis = 0. d1=0,d2=-2,d3=0,d4=2.

Answer 2

James' response was accurate