Solving Newton's Problem: 2 Masses Stacked on Each Other

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Homework Help Overview

The problem involves two masses, a 10kg block and a 20kg incline, with the goal of determining the force required to keep the block in equilibrium on the incline. The surfaces between the block and incline are frictionless, and the inquiry focuses on the forces acting on the block and the incline during this scenario.

Discussion Character

  • Conceptual clarification, Assumption checking, Exploratory

Approaches and Questions Raised

  • The original poster attempts to understand the forces acting on the block and the incline, expressing confusion over the free-body diagrams and the components of the applied force. Some participants suggest concentrating on the forces acting on the block and considering its acceleration to avoid sliding down the incline.

Discussion Status

The discussion is ongoing, with participants exploring the forces involved and questioning the directions of acceleration for both the block and the incline. Guidance has been offered to focus on the block's forces and the implications of Newton's laws, but no consensus has been reached on the complete understanding of the problem.

Contextual Notes

The original poster mentions having difficulty with the conceptual aspects of the problem and has sought additional help through office hours, indicating a potential lack of clarity in the problem setup or assumptions about the forces involved.

Myronnie
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Homework Statement


Ok, so I know how to solve ALL the other types of Newton problems that have been thrown at us. I can't understand conceptually when two masses are stacked on each other..I've tried to google it relentlessly and am going into my prof's office hours.

The surfaces between the 10kg block and 20kg incline are frictionless.
What is the force that has to be exerted on the incline so the 10kg block does not move up or down (aka is in equilibrium). The force is directed so that the incline is pushed to the left.
The problem is attached...
I've tried making free-body diagrams but to no avail - I just don't understand what forces exist in the free body diagrams! Is the force applied to the incline in two components relative to the block? I'm just so confused...


Homework Equations



Newton's third law


The Attempt at a Solution


Eh...many pages of useless scribble..
 

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Here's a hint or two to get you going. Concentrate on the block. What forces act on it? See if you can figure out what acceleration it must have in order not to slide down the incline.
 
Forces acting on the block - Normal force, Weight in two components (mgsintheta, mgcostheta), Contact force between incline and block ?
 
Myronnie said:
Forces acting on the block - Normal force, Weight in two components (mgsintheta, mgcostheta), Contact force between incline and block ?
The contact force between incline and block is the normal force. So only two forces act on the block: its weight and the normal force from the incline.

Now apply Newton's 2nd law. Which direction is the block being accelerated?
 
the block is being accelerated to the right opposite the horizontal component of weight (mgsintheta)..but the incline is being accelerated to the left by the force? I'm still lost =.=
 
Myronnie said:
the block is being accelerated to the right opposite the horizontal component of weight (mgsintheta)..but the incline is being accelerated to the left by the force? I'm still lost =.=
If the force F is pushing both block and incline to the left, what direction are both accelerated?
 

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