PLEASE HELP!
I need this 6 questions done!

What is the radius of the circular path ofa charged particle in a magnetic field?

When a book falls from a shelf to the ground without anyone pushing on it, no work is done on the book. true or false

Astone is dropped with no initial velocity from the top of a cliff and hits the ground a time of 3.9 s later. what is the height of the cliff, in units of meters? you may assume that air resistance is negligible. give the answer as a positive number question 15 a figure skater is rotating at a rate of 200 revolutions per minute. what is the angular speed, in units of rad/s? 200 o 20.9 12000 o 3.33