A 4.0\,\text {kg}4.0kg4, point, 0, start text, k, g, end text box slides with an initial speed of 3.0\,\dfrac{\text m}{\text s}3.0 s m 3, point, 0, start fraction, start text, m, end text, divided by, start text, s, end text, end fraction towards a spring on a frictionless horizontal surface. When the box hits the spring, the spring compresses and stops the box momentarily. The spring constant k=125\,\dfrac{\text N}{\text m}k=125 m N k, equals, 125, start fraction, start text, N, end text, divided by, start text, m, end text, end fraction.