A block of mass m = 0.40 kg slides on a horizontal

frictionless table with a speed v = 0.50 m/s.
It then runs

into and compresses a spring of spring
constant

k = 750 N/m. When the block is momentarily
stopped by

the spring, by what distance d is the spring
compressed?

Kf – Ki = - ½
kd2

0 – ½ mv2 =- ½
kd2

d = v sqrt (m/k)