Displacement Using Tabular Reimann Sum

[Qube]

Homework Statement

Find the displacement using a midpoint Reimann sum with 4 subintervals of equal width.

minute 0, 12, 24, 36, 48, 60, 72, 84, 96
ft/min -4, -4, 1, 4, 5, -6, 0, 5, 2

Homework Equations

Displacement is the final position minus starting position.

The Attempt at a Solution

Reimann sum:

delta x = 12

12[-4 + 4 + -6 + 5] I'm choosing all the ft/min values at the midpoints (which are 12, 36, 60, and 84).

12[-1] = -12 feet.

This isn't the correct answer however.

 

[Dick]

Homework Statement

Find the displacement using a midpoint Reimann sum with 4 subintervals of equal width.

minute 0, 12, 24, 36, 48, 60, 72, 84, 96
ft/min -4, -4, 1, 4, 5, -6, 0, 5, 2

Homework Equations

Displacement is the final position minus starting position.

The Attempt at a Solution

Reimann sum:

delta x = 12

12[-4 + 4 + -6 + 5] I'm choosing all the ft/min values at the midpoints (which are 12, 36, 60, and 84).

12[-1] = -12 feet.

This isn't the correct answer however.

Now why do you think Δx=12?

 

[Qube]

Oops. I was thinking of a Reimann sum with 8 subintervals I suppose. Delta x is 24. That would make a lot more sense.