In a chemical change the combination of what changes

Uwill get answer it brainliest will be awarded for →calculate the pressure exerted by a body having a mass of 30kg over an area of contact 400cm2.also explain it for every step there should be

If a 250-g mass is hung on two identical springs, hung side by side , and both support the 250-g mass, how much will each spring stretch?

In the graph, each sinusoidal curve shows the shape of a vibrating string at a different moment. for which values of x does a node occur? (let k = an integer from -2 to +2.) k + 0.5 0.5k k 2k + 1.5