A Massless Meter Stick on a Horizontal Frictionless Table Top

question 53

Multiple Choice

A massless meter stick on a horizontal frictionless table top is pivoted at the 80-cm mark.A force is applied perpendicularly to the end of the stick at 0 cm, as shown.A second force (not shown) is applied perpendicularly to the stick at the 100-cm end of the stick.The forces are in the plane of the table top.If the stick does not move, the force exerted by the pivot on the stick:

• A)must be zero
• B)must be in the same direction as and have magnitude
• C)must be directed opposite to and have magnitude
• D)must be in the same direction as and have magnitude
• E)must be directed opposite to and have magnitude

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Definitions:

Hyperpolarization

An increase in the membrane potential of a cell, making it more negative and less likely to fire an action potential.

Resting Membrane Potential

The electrical charge difference across the plasma membrane when a neuron or muscle cell is at rest.

Muscle

Tissue composed of fibers that can contract, causing movement of parts of the body.

Smooth Muscle Cells

Individual cells that make up smooth muscle, characterized by their ability to contract without voluntary control.