How do I solve for magnitude for displacement?

What do elements in a family tend to share. a.) similar periods b.) similar groups c.) similar atomic symbols d.) similar chemical properties and characteristics

An object weigh 40n in air ,weigh 20n when submerged in water,and 30n when submerged in a liquid of unknown liquid density.what is the density of unknown of liquid?

If an astronaut takes an object to the moon the following is true (choose only one). a the mass will change but the weight will be the same. b both the mass and the weight of the object will be the same. c the weight will change but the mass will be the same. d both the mass and the weight of the object will change.