The original poster is exploring the characteristics of an acceleration-time graph for a steel ball dropped from a table, specifically in the context of inelastic collisions. The discussion revolves around how to represent the acceleration during the ball's descent and ascent after bouncing.
There is an ongoing exploration of how to accurately depict the acceleration-time graph. Some participants provide guidance on the expected structure of the graph, emphasizing that the height of the bars remains constant due to the constant acceleration of gravity, while the widths decrease as the bounces become shorter. Clarifications are made regarding the implications of different graph shapes.
Participants are considering the implications of inelastic collisions and the nature of the bounces, which may affect the timing and representation of the graph. The original poster expresses uncertainty about the graph's shape and the representation of acceleration over time.
jarednjames said:You need to draw a per of axis where x = time and y = acceleration.
The acceleration of the steel ball is going from positive to negative. +9.8m/s^2 during the descent, -9.8m/s^2 during the ascent after the bounce. So the time goes from 0 to (time when it stops bouncing) and the acceleration goes from +9.8m/s^2 to -9.8m/s^2.
When the bar goes switches from above the x-axis to below it means the ball is changing direction (rising or falling).
Your axis should look roughly like this: http://sciencecity.oupchina.com.hk/npaw/student/glossary/acceleration_time_graph.htm and it also has an example of the bars to use.
You use blocks as the acceleration due to gravity being constant.
Your vertical height of the bar shows the acceleration due to gravity - your vertical height should always be +/- 9.8m/s^2.
Your horizontal width of the bar is the duration of the ascent / descent.
Your first bar (with positive acceleration of 9.8m/s as the ball is dropped) should be your widest and they will decay (get narrower) towards the right-hand side of the graph until eventually the ball stops bouncing - so there is no bar present.
Let me know if you require any more help,
Jared
thereddevils said:Thanks Jared, you are so helpful! I have a few questions here, the graph you linked me to has only one bar. Wouldn't the shape of the graph look like a horizontal pyramid, where the first 2 bars are the maximums and the rest decreases in height as time passes?
jarednjames said:The linked graph is an example, yours will have multiple bars, all the same height, but all with constantly diminishing widths. The first will be in the positive region, the second in the negative, the third in the positive and so on.
A pyramid instead of blocks would imply the acceleration is changing. This is not so. Acceleration due to gravity is constant and so a it is always 9.8m/s^2 during the balls ascent / descent. The height of the bars will not decrease as the acceleration is constant. The width however will, as the height of each bounce decreases the time the bounce takes will decrease and so the width of the bars will become less.
Everything I put in my first post stands.
The attachment to this post is an example of what your graph should look like.
Jared