An Automatic Rifle Fires 0

question 26

Multiple Choice

An automatic rifle fires 0.040-kg projectiles at a speed of 800 m/s.If the gunner holding the rifle in her hands can exert an average force of 160 N against the gun,the maximum number of projectiles she can fire in one minute is

• A)15
• B)300
• C)800
• D)4000
• E)48,000

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Definitions:

Hyperpolarization

An increase in a cell's membrane potential, making it more negative inside compared to the outside and further from the threshold that causes action potentials.

Absolute Refractory Period

A period immediately following the stimulation during which a nerve or muscle is unresponsive to further stimulation.

Second Messenger System

A method of cellular signaling where the signal from a first messenger is transferred to a secondary molecule inside the cell to elicit a physiological change.

Protein Kinase

An enzyme that modifies other proteins by chemically adding phosphate groups to them, thereby altering their function.