Question

A 85 Kg block of ice is being pushed in a straight rough road. The force exerted on the ice 300 N and acceleration of the entire system is 10 m/s^2. What is the friction force between the ice and the rough road.

Answer 1

$$ma=F-F_f$$

$$F_f=F-ma\\ =\rm 300\: N-8.5\: kg\times 10\: m/s^2=215\:\rm N$$