Home › AP Physics C: Mechanics › Physics › Friction, Drag, and Elasticity › In a take-home experiment, a coin is placed on a…
In a take-home experiment, a coin is placed on a textbook that is then tilted until the coin slides down at a constant velocity. What does measuring the tilt angle let you find?
AThe coefficient of kinetic friction, equal to the tangent of the tilt angle
BThe coefficient of static friction, equal to the sine of the tilt angle
CThe mass of the coin, found from the tilt angle alone
DThe normal force on the coin, independent of its weight
Answer & Solution
Correct answer: A. The coefficient of kinetic friction, equal to the tangent of the tilt angle
1. At a constant velocity, the net force along the slope is zero, so kinetic friction exactly balances the weight component along the slope.
2. Writing mu_k mg cos theta equal to mg sin theta and solving gives mu_k equal to tan theta.
3. This means a single angle measurement gives the coefficient of kinetic friction directly, not the static coefficient.
4. The coin's mass cancels out of the equation entirely, so the angle alone cannot reveal the coin's mass or the numeric normal force.
_Source: OpenStax College Physics (CC BY 4.0), Ch 5 "Further Applications of Newton's Laws: Friction, Drag, and Elasticity", section 5.1 Friction_
Related questions
According to the source, at roughly what point in life does the gradual physiological reduIf human arteries were rigid instead of elastic, what would you notice about your pulse, aA human tendon shows a nonlinear stress-strain curve. What does the source call the very fWhat example does the source give of a practical application of bulk compression on solidsUnlike most materials, what unusual behavior does water show when it freezes, according toAt a depth of 5.00 km in the ocean, the force per unit area on seawater is 5.00 times ten It is relatively easy to compress a gas but extremely difficult to compress a liquid or a What does the source say about the shear moduli of liquids and gases?