You attach a cart with a mass of 2.6 kg to a spring and compress the cart-spring system so that the cart is located 40 cm behind the springs equilibrium point. If the cart is released and has a velocity of 2.0 m/s when it reaches the equilibrium position, what is the spring constant k?

Could someone . i have tried to solve myself but my calculation is off

An object in mechanical equilibrium is an object

Listed following are various physical situations that describe how light interacts with matter. match these to the appropriate category. 1) transmission? -visible light meets clear glass -visible light does not pass through a black wall -red light hits a red sweatshirt -light comes from your computer screen -cell phone signals pass through walls -blue light hits a red sweatshirt -white light hits a white piece of paper -light comes from a light bulb