The only force acting on a 2.0-kg object moving along the x axis is shown. If the velocity v_x is −2.0 m/s at t = 0, what is the velocity at t = 4.0 s? A) −2.0 m/s B) −4.0 m/s C) −3.0 m/s D) +1.0 m/s E) +5.0 m/s

Question

Quizplus · Accepted Answer

Since the force acting on the object is constant, we can use the kinematic equation: 
v = v0 + at 
where v is the final velocity, v0 is the initial velocity, a is the acceleration, and t is the time.

We can determine the acceleration from the force: 
F = ma 
a = F/m = 4 N / 2.0 kg = 2.0 m/s^2

Substituting the known values: 
v = -2.0 m/s + (2.0 m/s^2)(4.0 s) = -2.0 m/s + 8.0 m/s = 6.0 m/s

Therefore, the velocity at t = 4.0 s is C) -3.0 m/s.

The Only Force Acting on a 2