Skip to main content
Physics LibreTexts

03. Drawing Motion Graphs

  • Page ID
    465
  • [ "article:topic", "authorname:dalessandrisp" ]

    Let’s look at the situation again:

    In the shot put, a large mass is thrown at an angle of 22oabove horizontal, from a position of 2 m above the ground, a horizontal distance of 25 m.

     Kinematics Picture 5.png

    The verbal representation of the situation has already been translated into a pictorial representation, the motion diagram. A careful reading of the motion diagram allows the construction of the motion graphs.

     

    Drawing the position vs. time graph

    First, examine the position of the shot put as it moves through the air. Remember, the analysis of the horizontal position must be independent of the analysis of the vertical position.

    Horizontal Position

    From the motion diagram, the shot put starts at position zero, and then has positive, increasing positions throughout the remainder of its motion. The horizontal position increases by even amounts in even time intervals.

    Kinematics Picture 6.png

    Vertical Position

    The shot put starts at position zero, increases its vertical position at a rate that is decreasing, then begins to decrease its vertical position at a rate that is increasing, even as it drops to negative positions.

     

    Kinematics Picture 7.png

    Typically, both the horizontal and vertical positions are displayed on the same axis.

     

    Kinematics Picture 8.png

    Drawing the velocity vs. time graph

    In the horizontal direction, the rate at which the position changes is constant. Hence, the horizontal component of velocity is constant, and positive. In the vertical direction, the velocity component begins positive, decreases to zero, and then increases in the negative direction.

    Kinematics Picture 9.png

    Drawing the acceleration vs. time graph

    From the motion diagram, the acceleration of the shot-put can be determined to be directed downward at every point. Thus, the horizontal component of acceleration is zero and the vertical component is negative, and approximately constant due to our model's approximations.

    Kinematics Picture 10.png

     

     

    Paul D’Alessandris (Monroe Community College)