Can someone please help me? (UsaTestPrep)

Lets say that an object of a certain volume has a certin mass. what happens to its mass when you double its volume?

Abookcase has a mass of 38 kg and the coefficient of friction between it and the floor is 0.82 what is the maximum force of friction between the bookcase and the floor a 372n b 305n c 412n d 449n

Positrons are spontaneously emitted from the nuclei of