A 300-M-Long Ladder,weighing 200 N,leans Against a Smooth Vertical Wall with with Its

question 55

Multiple Choice

A 3.00-m-long ladder,weighing 200 N,leans against a smooth vertical wall with its base on a horizontal rough floor,a distance of 1.00 m away from the wall.The ladder is not completely uniform,so its center of gravity is 1.20 m from its base.What force of friction must the floor exert on the base of the ladder to prevent the ladder from sliding down?

• A)93.3 N
• B)130 N
• C)28.3 N
• D)102 N
• E)150 N

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Definitions:

Pineal Gland

A small endocrine gland in the brain that produces melatonin, a hormone that affects the modulation of wake/sleep patterns and seasonal functions.

Melatonin

A hormone that aids regulation of circadian rhythms; bright light reduces production and darkness increases production.

Melatonin

A hormone produced by the pineal gland that regulates sleep and wakefulness, often associated with the body's circadian rhythms.

Slow-Wave Sleep

Stages 3 and 4 of deep sleep, where a person is substantially less conscious and is hard to awaken; EEGs reveal large, regular delta waves.