There are (one can say) three coequal theories of motion: Newton’s second law, stating that the total force on an object causes its acceleration; the work–kinetic energy theorem, stating that the total work on an object causes its change in kinetic energy; and the impulse–momentum theorem, stating that the total impulse on an object causes its change in momentum. In this problem, you compare predictions of the three theories in one particular case. A 3.00-kg object has velocity 7.00j m/s. Then a total force 12.0i N acts on the object for 5.00 s.
(a) Calculate the object’s final velocity, using the impulse–momentum theorem.
(b) Calculate its acceleration from a = (vf ─ vi) Δt
(c) Calculate its acceleration from a = ∑F/m,
(d) Find the objects vector displacement from Δr = vit + ½ at2
(e) Find the work done on the object from W F2∙Δr.
(f) Find the final kinetic energy from ½ mvf 2 = ½ mvf ∙vf∙
(g) Find the final kinetic energy from ½ mvi2 + W.