7. Friction, Inclines, Systems

A 1.0-cm-diameter, 2.0 g marble is shot horizontally into a tank of 20°C olive oil at 10 cm/s. How far in cm will it travel before stopping?

Which of the following lists correctly identifies the four main types of friction encountered in physics?

An object with cross section A is shot horizontally across frictionless ice. Its initial velocity is v₀ₓ at t₀ = 0 s. Air resistance is not negligible. Show that the velocity at time t is given by the expression $v_x=\frac{v_{0x}}{1+C_d\rho A{v}_{0x}t/2m}$.

When a car tire is skidding on a road, how does increasing the speed of the tire affect the kinetic friction force between the tire and the road?

Which of the following material pairings would most likely result in the greatest kinetic friction ($f\_k$) when sliding against each other?

A $45.0$-kg crate of tools rests on a horizontal floor. You exert a gradually increasing horizontal push on it, and the crate just begins to move when your force exceeds $313$ N. Then you must reduce your push to $208$ N to keep it moving at a steady $25.0$ cm/s. Suppose you were performing the same experiment on the moon, where the acceleration due to gravity is $1.62$ m/s².

(i) What magnitude push would cause it to move?

(ii) What would its acceleration be if you maintained the push in part (b)? Note: Part (b) asked what push you must exert to give it an acceleration of $1.10$ m/s².

Kinetic friction acts on a moving object sliding across a surface. How does kinetic friction affect the speed of the object over time?

You throw a baseball straight upward. The drag force is proportional to $v^2$. In terms of $g$, what is the $y$-component of the ball's acceleration when the ball's speed is half its terminal speed and it is moving back down?

Which of the following scenarios best demonstrates kinetic friction?

If the skydiver's daughter, whose mass is $45$ kg, is falling through the air and has the same $D$ ($0.25$ kg/m) as her father, what is the daughter's terminal speed?