Question

The tension in a rope pulling a log is 100N, the mass of the log is 50kg and the frictional force on the log is 20N. What is the acceleration of the log?

Answer 1

From the second Newton's law:

$$ma=F_{net}=T-F_f$$

The acceleration of the log:

$$a=\frac{T-F_f}{m}=\frac{100-20}{50}=1.6\frac{m}{s^2}$$