4. The position vs. time graph for an object is shown. Position (a) Describe which feature of the position versus time graph shows that the object is not at rest at time t = 0. 2 4 5 Time, sec Velocity (b) Sketch a velocity vs. time graph that is consistent with the position vs. time graph. 5 Time, sec 5. An object moves in one dimension. Its motion is Position, (m) represented on the x vs. t graph shown at right. (a) Is the object speeding up, moving with constant speed, or slowing down? Explain how you can tell. 2 3 4 5 Time, sec -2 -4 (b) What is the velocity of the object at t = 0? (Be sure to specify both direction and magnitude.) -6 (c) What is the position of the object at t = 0? (d) Write an algebraic expression for the position of the object as a function of time, in the form x ( t ) =