At the beginning of Activity 1 of this unit, you sketched a speed-time graph for a soccer ball that was given a quick kick and then slowed to a stop as it rolled across the grass. Sketch this graph again on the following page, with any changes from the original you wish to make.

On the graph use different colored pencils to indicate:

a)  The section (or sections) of the graph during which there was a contact push/pull interaction between the foot and the ball

b)  The section (or sections) of the graph during which a force acted on the ball in the same direction as its motion

Explain your reasoning for choosing these sections.

Answer in below section.

Step-by-step explanation

For graph see the attached file

The graph have three different region:

Yellow curve: When soccer ball pushed by player.

Blue curve: When soccer ball moving with constant speed without any contact.

Purple curve: When soccer ball come to contact to grass and stops at end point. 

On the graph I have used different colored pencils to indicate:

a)  The section of the graph during which there was a contact push interaction between the foot and the ball: The section indicated in yellow color. 

Reasoning : As you know when soccer ball is pushed by foot the ball will gain highest speed in few seconds so the graph will have largest slope for this scenario.   

b)  The section of the graph during which a force acted on the ball in the same direction as its motion: The section indicated in yellow color. 

Reasoning : As you know when soccer ball is pushed by foot the ball will gain speed with time that indicates the positive slope of the graph. The slope represents the acceleration of the ball i.e. the Force direction is same as motion or speed of the ball.