What is the force of static friction preventing a box that weights 67 N from moving if the coefficient of static friction is 0.512

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,?

Why does the liquid rise up through the dip tube when the valve is open

(asap) uneven heating of the earth's surface is due primarily to the position of the equator, north pole, sun, or moon?