Why the time is the quarter of a period?

[zade70]

Homework Statement

When the brick with mass 3 kg is hanged in a spring, it is lengthened 25 cm. If we lengthen the spring with 15 cm more and leave it free how may times does the brick take to come back to the equilibrium position

Homework Equations

In the solution it says t=T/4

The Attempt at a Solution

I understand d the other part, but why is t=T/4 (t-time, T-period)

 

[haruspex]

Homework Statement

When the brick with mass 3 kg is hanged in a spring, it is lengthened 25 cm. If we lengthen the spring with 15 cm more and leave it free how may times does the brick take to come back to the equilibrium position

Homework Equations

In the solution it says t=T/4

The Attempt at a Solution

I understand d the other part, but why is t=T/4 (t-time, T-period)

Consider three positions, the lowest position of the oscillations (i.e. the release position), the equilibrium position, and the highest oscillation position. If it takes time t to rise from lowest to equilibrium, how long will it take to return to the lowest position?

 

[Lexadis]

This diagram might help?