PLS HELP !! the first two questions i need help understanding!

During the experiment if you could triple the breakaway magnetic force with all other quantities left unchanged, what is the new value for the critical velocity if it was v0 (initial velocity), initially? (b) now if you halved the radius with all other quantities left unchanged, what is the new critical velocity if it was v0 (initial velocity), initially? (c) if during the experiment, critical velocity quadrupled with all other quantities left unchanged, what is the new breakaway force if its magnitude was initially f0,?

If there's a small amount of friction between two surfaces, the result could be select all that applya. no movement b. heatc. a little bit of movementd. sliding around

By what factor does the drag force on a car increase as it goes from 65 to 110 km/h?