To find the instantaneous vertical velocity at 6 seconds using the graph you drew, you can follow these steps:
Step 1: Identify the point on the graph that represents 6 seconds on the x-axis.
Step 2: Read the corresponding value on the y-axis. This represents the vertical displacement at 6 seconds.
Step 3: Calculate the slope of the tangent line at that point. The slope of the tangent line represents the instantaneous vertical velocity at that specific instance.
Now, let's answer your second question. In this problem, since you are dealing with vertical motion (y-coordinate), you do not need to use the linear equation for horizontal motion (x-coordinate). The horizontal motion is not directly involved in finding vertical displacement or velocity.
Remember that horizontal motion and vertical motion are separate components and can be treated independently if there is no interaction between them.
I hope this clarifies how to find the instantaneous vertical velocity and the relevance of the horizontal motion equation in this problem.