An unknown substance has a mass of 15 g and a volume of 4 cm3. calculate the density of the unknown substance.

Samir watches a 100-minute movie on his spaceship. maria's spaceshipe flies in the same direction as samir's spaceship but she observes his move to last 125 minutes and his spaceship to be 40 m long. how long does samir observe his own spaceship to be? according to an observer on earth, planet x is stationary. maria and samir depart earth on their spaceships at the same time, each flying at 0.5c. maria flies toward planet x and samir flies in the opposite direction. according to maria, her voyage to planet x takes 9 years. how many years does marias voyage take according to samir?

What is the increase in density of a medium due to wave travel?

The voltage applied across a given parallel-plate capacitor is doubled. how is the energy stored in the capacitor affected?