How can I solve these problems?

If the chemical properties of a substance remain unchanged and appearance or shape of a substance changes it is called a ?

Consider the following position function. find (a) the velocity and the speed of the object and (b) the acceleration of the object. bold r left parenthesis t right parenthesisr(t)equals=left angle 6 t superscript 4 baseline comma 2 t cubed right angle6t4,2t3 for tgreater than or equals≥0

Explain what it means to view something from a frame of reference. provide an example that illustrates your explanation. (4 points)