Circle the right answers.

I. A physical quantity E is defined as E = ½ mv², where m is mass and v is velocity. What is the unit of E?

    A.    m²s^-1
    B.    m²s^-2
    C.    Kgm²s^-2
    D.    Kgms^-2
    E.    None of above.

    Ans.    C

II. A toy train is running on a circular rail of 2m in diameter. It completes one circle in 20 seconds. Which of the following statement is false:

    A.    The net displacement of the train after completing one circle is 0.
    B.    The train is moving with a constant velocity.
    C.    If the train doubles the speed, it will half the time to complete one cycle.
    D.    The speed of the train is 0.31 m/s.
    E.    The average velocity of the train is 0 m/s over one period of time to complete the circle.

    Ans.    B

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

To the best of your judgment, which of the following given time has zero acceleration:
 
    A.    t = 1s
    B.    t = 5s
    C.    t = 7s
    D.    t = 9s
    E.    t = 13s

    Ans. E