- #1
decentfellow
- 130
- 1
Homework Statement
Block ##A## of mass ##m## is placed over a movable wedge of mass ##m##. Both the block and the wedge are placed over a fixed incline plane. Assuming all the surfaced to be smooth, calculate the displacement of the block ##A## in the ground frame reference in ##1s##.
Homework Equations
$$\vec{F}=m\vec{a}$$
The Attempt at a Solution
Before beginning, the question that I posed above is a solved example, and I am just confused about the motion of the block ##A##. So here goes.
The solution says that "Let acceleration of wedge in ground's frame is ##a## down the plane. The acceleration of block ##A## will be ##a\sin\theta## vertically downward"
Now, my problem is with the very first line of the solution, how can the block only have an acceleration down the plane, though in the solution, to justify the first line it is stated that "From FBD of A it is clear that Block A cannot accelerate horizontally, i.e. in ##x-##direction because there is no force acting on the block ##A## in ##x-##direction, hence block ##A## can accelerate in ##y-## direction only."
Though the explanation seems right in its place but before seeing the solution, my line of thought regarding the question was that as the block is constrained to move with the movable wedge hence it has an acceleration in the the direction along the plane. I don't know why but the explanation in the solution is just not sinking in.
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