Friction-less wedge physics problem

[holyko]

A 2.0-kg body rests on a frictionless wedge that has an inclination of 65.0° and an acceleration a to the right such that the mass remains stationary relative to the wedge. Find a

This is one of the question i had to do for HW.
Not really asking for an answer but it would be great if you provide one with a semi detail equation

I just don't get how is a body at rest yet accelerating! I probably misinterpret the question and I hope someone will point out where I misunderstood. Thank You

 

[Sirus]

What they mean is that the wedge with the mass on it is being acclerated (along the floor, for example) in a way that the mass does not slide down the wedge as it would if it were stationary. Try using some basic principles. Very interesting problem.

 

[holyko]

Thx for pointing out my misinterpertation ^_^. Now, the question made more sense.


Ok, I tried doing the question but I got the wrong answer and this is what I did:

I thought maybe mass doesn't matter in this situation because all object has the same accelartion due to gravity
so i just went acelaration to the right = 9.8 x sin 65 x sin 25

The sin 65 was to find the accelartion for the body sliding down the incline
this acceleration is parallel to the incline

Then i did a bit of geometry to figure out that sin 25 will give me "a" to the right.

so, was i wrong about ignoring the mass or what?

 

[Pyrrhus]

Try understanding this problem

https://www.physicsforums.com/showthread.php?t=44607

 

[Doc Al]

so, was i wrong about ignoring the mass or what?

I'm afraid so.
In any problem concerning acceleration or force, you'd better consider the mass.

Think this way. There are two forces acting on the body: (1) the normal force from the wedge, and (2) the weight. Hint: in the vertical direction, the body does not accelerate; in the horizontal direction, it does. Apply $\vec{F_{net}} = m \vec{a}$.