What tools are used to find the mass of an object

Which equation is used to calculate the magnetic force on a charge moving in a magnetic field

Need with these questions . need the answers in a rush for these questions are the answers i put down are correct or not? ?

Both destructive and constructive, the natural event seen here, is important in destroying and creating landforms on earth. what is this event called? a) deposition b) flooding c) landslide d) sedimentation