Newton's Law states the force (F) exerted by a point with mass M on another points of mass m is F=GmM/r^2

Here G is a constant and r is the distance between the two points in meters. Let r be a function of time in seconds, where r(t) = 10^6sin( π t/300). (To clear confusion: r(t) equals to 10 to the power of 6 times sin( pi times t over 300))

What is the rate that F is changing with respect to time when t = 50, G = 6.673 x 10^-11 Nm^2/kg^2, m=70kg, and M = 6x10^24 kg?

Thank you for your time and help!