Force on 2 Masses Homework: FBD, N3, Acceleration & Force

[loka]

Homework Statement

Two blocks, of mass M and m, are in contact on a horizontal, frictionless table (w/ the block of mass M on the left and block of mass m on the right). A force F₁, is applied to the block of mass M and the two blocks move together to the right.

a. Draw a FBD

b. Suppose the larger block M exerts a force F₂ on the smaller mass m. By N3, the smaller block m exerts a force F₂ on the larger block M. Argue whether F₁ = F₂ or not.

c. Derive an expression for the acceleration of the system.

d. Derive an expression for the magnitude of the force F₂ that the larger block exerts on the smaller block.

e. Choose different values of M and m and compare the magnitudes of F₁ and F₂

Homework Equations

The Attempt at a Solution

a. see attachment

b. acc. to N3, "for every action, there's an equal and opposite reaction force" so F1 = F2 >> the thing is what if M is accelerating?

c. a = F_net/m

d. F₂ = ma

...is what I'm doing here...right?

 

[Pinu7]

b. acc. to N3, "for every action, there's an equal and opposite reaction force" so F1 = F2 >> the thing is what if M is accelerating?

First off, if my hand was the force, the reactionary force is the force the block applies on my hand.

Force depends on mass and acceleration. Aren't the blocks accelerating equally? And if they are of different masses how can the force on block 2 be the same as the one on block 1?

"c. a = Fnet/m"

First,expand Fnet and also the total mass is not m since there are two blocks of mass M and of mass m.

 

[nlightner]

e. Yes, you are on the right track with your answers for parts b, c, and d. For part e, you can choose different values for M and m and see how it affects the magnitudes of F1 and F2. You can also try changing the direction of the applied force F1 and see how that affects the system. This will help you understand the relationship between the masses, forces, and acceleration in this system.