What is the compare the strength of static, sliding, and rolling friction

What is the measure of a change in an objects velocity?

Select all the correct answers. which changes will increase the rate of reaction during combustion? decreasing the area of contact between the reactants adding more oxygen to the reaction removing heat from the reaction changing the reactants from solid form to powdered form lowering the exposure of the reactants to air

What is the difference between mass density and weight density?