A 50-Kg Crate Is Resting on a Horizontal Plank

question 17

Multiple Choice

A 5.0-kg crate is resting on a horizontal plank. The coefficient of static friction is 0.50 and the coefficient of kinetic friction is 0.40. After one end of the plank is raised so the plank makes an angle of 30 with the horizontal, the force of friction is:

• A) 0
• B) 18 N
• C) 21 N
• D) 22 N
• E) 44 N

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Definitions:

Continental Crust

The type of Earth’s crust that underlies the continents and the continental shelves; average granitic composition, but includes diverse types of material.

Oceanic Crust

the part of the Earth's crust that underlies the oceans, thinner and denser than continental crust.

Upper Mantle

The upper mantle refers to the portion of the Earth's mantle that lies just beneath the crust, extending down to a depth of about 660 kilometers, involved in tectonic movements and convection currents.

Lower Mantle

The deeper section of the Earth’s mantle extending from 670 kilometers below the surface to the outer core, characterized by high pressure and temperature.