Circle the right answers.

I. Which of the following additions or subtractions is not possible because of inconsistency in units? In all expressions, x is distance, v is speed, a is acceleration, t is time, and m is mass.

    A.    v²-2ax

    B.    x + ½ at²
    C.    va - 
    D.    ma + 
    E.    vx - a²t³

    Ans. : D

II. A stone is thrown vertically upward. It reaches a maximum height (below the ceiling) and then falls back. Assume the upward direction as positive direction, and the origin at the ceiling. Which of the following statement is false:

    A.    The acceleration of the stone is 0 m/s² at the highest point.
    B.    The displacement (from the origin) of the stone is always negative.
    C.    The velocity of the stone is negative when it is falling down.
    D.    The stone will reach a lower height if it is thrown with a smaller upward velocity.
    E.    The velocity of the stone is 0 m/s at the highest point.

    Ans. : A

III. The position of an object is located in the path as follow:

At which of the following time interval the object is traveling with the highest average speed:

    A.    From t = 0s to t = 1s
    B.    From t = 4s to t = 5s
    C.    From t = 6s to t = 7s
    D.    From t = 8s to t = 9s
    E.    From t = 12s to t = 13s

 Ans. : D