Dear all, I got a question, i'm designing a setup used for measuring shear and compression forces in foam samples. A machine moves a block with a constant speed. In that way the samples are compressed with a force under a certain angle. Now the sample are experiencing a shear and compression force. It are these force I want to measure over time. The setup looks like this: I can measure a vertical force Fv and a horizontal force Fh. With these two forces I want to calculate the compression force Fc and the shear force Fs. Now if I write a equilibrium of block 1 and I neglect the friction force on top of the block I get this: Is this a correct way to measure the shear and compression forces of the samples ? If i don't neglect the friction on the top block then I have to write a momentum equation. This means if I place my samples a bit higher or lower between the blocks all my calculation will be wrong ?