Answer
See work.
Apply Newton’s second law.
$\Sigma F_x=ma_x$
Work Step by Step
a. The maximum net force occurs when the acceleration is maximum value. This maximum force occurs between 2.0 s and 4.0 s.
From the graph, we find the maximum net force.
$\Sigma F_x=ma_x=(4.50kg)(10.0m/s^2)=45.0 N$
b. The net force is constant when the acceleration is constant, between 2.0 s and 4.0 s.
c. The net force is zero when the acceleration is zero, at t=0 and t=6.0s.
