About acceleration of block with respect to wedge and ground

1. Dec 30, 2011

caffe

Hi friendz I have a problem.
If a block of mass m is placed over the wedge such that there is no friction then what is the acceleration of block
1with respect to wedge
2 with respect to ground
My sir said that it is different.Is it so.

2. Jan 1, 2012

JHamm

For the first one you just need to consider the wedge as fixed. For the second one add the negative acceleration of the wedge to the block.

3. Jan 1, 2012

caffe

Here wedge is stationary.Now please tell me the acceleration of block with respect to wedge and ground.

4. Jan 1, 2012

Staff: Mentor

Please state the exact problem you are trying to solve.

5. Jan 1, 2012

caffe

My question is that there is a stationary wedge on which block is placed and all the sutfaces are smooth.Now according to mg physics teacher the acceleration of block with respect to wedge is gsin@ and with respect to ground is g .Is it true.But according to my knowledge as we read that accelaration of any body with respect to two different inertial frame is same.Now here block and ground are two different inertial frames.Then why acceleration of block with respect to wedge and ground different.

6. Jan 1, 2012

Staff: Mentor

OK, the wedge is fixed and not free to slide. But there's no friction between block and wedge.
No. The acceleration of the block with respect to both the wedge and the ground is gsinθ.
Your thinking is correct. The wedge and ground are both at rest in the same inertial frame. So the acceleration of the sliding block is the same with respect to each.

7. Jan 1, 2012

Thanks .
Sir.....