Can you guys please answer this questions

Example 15.5 Using conservation of energy A 500 3 block on a spring is pulled a distance of 20 cm and released. The subsequent oscillations are measured to have a period of 0.80 s. a. At what position or positions is the block's speed 1.0 m/s? b. What is the spring constant? PREPARE The motion is SHM. Energy is conserved. SOLVE 1 a. The block starts from the point of maximum displacement, where E = U = EkAz. At a later time, when the position is x and the speed is '0, energy conservation requires 1 1 2 _ 1 2 Solving for x, we nd )6: AzmVZ= [ll(1)2 k a) where we used k/m = 602 from Equations 15.23 IQ. The angular frequency is easily found from the period: a) = 22r/T = 7.85 rad/s. Thus 1. 2 x = 1{(020111)2 (%) = $0.15 m = :15 cm There are two positions because the block has this speed on either side of equilibrium. b. Although part a did not require that we know the spring constant, it is straightforward to nd from Equations 15.239: T=27r1/% k= \"2'" m=31N/m T2 (0.80 s)2