Question

15 points---- Anyone wanna help :(

Answer 1

The force F newtons between two magnetic poles is given by the formula

F = \displaystyle\frac{1}{500r^{2}}  where r m is their distance apart.

Find the rate of change of the force when the poles are 0.2 m apart and the distance between them is increasing at a rate of 0.03 ms^-1"

\displaystyle\frac{dF}{dt} = \frac{dr}{dt}*\frac{dF}{dr}

dr/dt = 0.03 ms^-1 and df/dr = -1000r^-3.....where r = 0.2m so don't i just do for df/dr, -1000*(0.2^-3) and then multiply it by 0.03???