PhysicsLAB CP Workbook
Force Vectors and the Parallelogram Rule

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Refer to the following information for the next six questions.

The heavy ball is supported in each case by two strands of rope. The tension in each strand is shown by the vectors. Use the parallelogram rule to sketch the resultant of each vector pair on your papers. Then describe your answers in the blanks provided.




Is your resultant vector, R,  the same for each case? 

How do you think the resultant vector compares to the weight, W, of the ball? 

Part II

Now let's do the opposite of what we've done above. More often, we know the weight of the suspended object, but we don't know the rope tensions. In each case below, the weight of the ball is shown by the vector W. Each dashed vector represents the resultant, R, of the pair of rope tensions. Note that each is equal and opposite to the vector W (they must be; otherwise the ball wouldn't be at rest).

Refer to the following information for the next four questions.

On your papers, construct parallelograms where the ropes define adjacent sides and the dashed vectors are the diagonals. Next, draw rope-tension vectors, clearly showing their relative magnitudes. Describe your answers in the blanks provided.




How do the relative lengths of the sides of each parallelogram compare to rope tensions?

Refer to the following information for the next two questions.

A lantern is suspended as shown. Draw vectors to show the relative tensions in ropes A, B, and C.
Explain the relationship between: vectors A + B and vector C

Explain the relationship between: vectors A + C and vector B

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