NEWTON'S SECOND AND THIRD LAWS

Mech

$31$

I. Applying Newton's laws to interacting objects; constant speed

Three identical bricks are pushed across a table at constant speed as shown. The hand pushes horizontally. $($Note: There is friction between the bricks and the table.$)$

Call the stack of two bricks system A and the single brick system B$.$

A$.$ Compare the net force $($magnitude and direction$)$ on system A to that on system B$.$ Explain how you arrived at your comparison.

B$.$ Draw separate free$-$body diagrams for system A and system B$.$ Label each of the forces in your diagrams by identifying: the type of force, the object on which the force is exerted, and the object exerting the force.

C$.$ Is the magnitude of the force exerted on system A by system B greater than, less than, or equal to the magnitude of the force exerted on system B by system A$?$ Explain.

Would your answer change if the hand were pushing system B to the left instead of pushing system A to the right? If so$,$ how? If not, why not?

D$.$ Identify all the Newton's third law $($action$-$reaction$)$ force pairs in your diagrams by placing one or more small $"x"$ symbols through each member of the pair $($i$.$e$.,$ mark each member of the first pair as longrightarrow, each member of the second pair as $,4,$ etc.$).$

What criteria did you use to identify the force pair$($s$)?$

Is your answer to part C consistent with your identification of Newton's thind law $($or action$-$reaction$)$ force pairs? If so$,$ explain how it is consistent. If not, resolve the inconsistency.