THE UNIVERSITY OF BRITISH COLUMBIA
 
Science 1 Physics Assignment # 3:
 
The Vulgar Mechanic
 
Wed. 27 Sept. 2000 - finish by Wed. 04 Oct.

1.

Dragging Line

On the Lady Rose we did a crude experiment to see how the drag force on a fishing line varied with the length of line in the water (assuming the boat kept moving at constant speed, which it pretty well did). With different lengths of line in the water the drag force was measured by seeing how much it stretched a long elastic shock cord. After correcting for the length of line not actually in the water etc., the following results were obtained:

Length of Line in Water [ft]	Stretch of Shock Cord [in]
$154.4 \pm 0.3$	$11.0 \pm 0.5$
$137.4 \pm 0.3$	$10.25 \pm 0.5$
$120.4 \pm 0.3$	$7.0 \pm 0.5$
$103.4 \pm 0.3$	$3.25 \pm 0.25$
$86.4 \pm 0.3$	$2.5 \pm 0.25$

(a)

Assumptions: How should the actual drag force relate to what was measured? What are some likely errors in this relationship? What other systematic errors are likely?

(b)

Power Law Fit: If we believe that the drag force is proportional to some power of the length of line in the water, what do you estimate that power to be? A simple graphical construction should suffice to answer this question. Restrict your uncertainty estimation to ``judgement calls'' - do not attempt a rigourous calculation!

. . . and Tipler Ch. 4:

(4$^{\rm th}$ Edition) problems 8, 47, 65 and 95

. . . and Tipler Ch. 5:

(4$^{\rm th}$ Edition) problems 13, 40, 57, 66 and 84