Does the amount of mass entering a control volume have to be equal to the amount of mass leaving during an unsteady-flow process?

Two polarizers are oriented at 70∘∘ to one another. unpolarized light falls on them. what fraction of the light intensity is transmitted?

Carbon-14 is a radioactive element that undergoes beta decay. which force is responsible for allowing carbon-14 to become stable? electromagnetic gravitational weak nuclear strong nuclear

What object a collides with object b and bounces back its final momentum is?