## Questions 18-19
A block of mass 3 kg , initially at rest, is pulled along a frictionless, horizontal surface with a force shown as a function of time t by the graph above.
18. The acceleration of the block at t=2s is
(A) 3/4m/s2
(B) 4/3m/s2
(C) 2m/s2
(D) 8m/s2
(E) 12m/s2