Three Block Problem: Friction and Contact Forces

Physics Ninja looks at a problem involving 3 blocks sliding across a frictionless surface. Free Body diagrams are shown and we solve for the Contact Force and the force of friction.

[@yousefnoori]

Thank you so much for this! I'm a freshman in Engineering and I've always had trouble understanding kinematic physics, but this video has simplified so much for me!

[@wiimaster2847]

Your way of explaining the normal forces with the blocks (specifically with block 2 and block 3) was very helpful. I never had a complete grasp on how normal forces work when it comes to blocks stacked on top of each other and this makes a lot of sense.

[@shadowkxm]

Hey man. Thanks so much for this. From the bottom of my heart. God bless you

[@user-eo5sn6zd1i]

thank you so much because of you my confidence doubled for tomorrow's test i literally found this concept impossible to understand until you did it in 16min !!!!

[@PhysicsNinja]

Good luck! You’ve got this

[@ebucehil9386]

THANK YOU MR. PHYSICS NINGOAT

[@assemhefny627]

marvelous

[@RinaNewhouse]

Thank you so much for uploading these videos! I am in an engineering-based physics class, and your videos have been extremely helpful for my (hopeful(!)) success in the class. :D

[@PhysicsNinja]

Good luck with your class. Things will get hard, don’t worry just keep working. Eventually it will click. You’ve got this!

[@RinaNewhouse]

@@PhysicsNinja ☺

[@sivakrishnan5175]

Thank you so much, it use for my examination 🤗

[@user-kx8sw3wo3c]

عاشت ايدك دكتور❤

[@silvermist6891]

Thanks sir.

[@user-zb6xj1vh3c]

This is very nice vedeo .

[@rafigrewati6417]

If F was higher like 60N we would have ended with Ft being more than the max static friction .... does that mean that m3 will slide over m2 having different acceleration although the assumption was that they are moving together? ... it would also mean that we should always compare the two friction forces
Tanks - Nice video by the way

[@PhysicsNinja]

Yes, if the we are beyond the maximum force of friction it means that the top block will slip. We can no longer assume that the acceleration will be the same for the top block. If the top block is slipping we can then use the kinetic friction formula to find the force of friction and the acceleration of the top block.

[@boboganbobogan9297]

@@PhysicsNinja where would that kinetic friction force be pointed to? To the right or left?