Dynamics | "A smooth 2 kg collar is attached to a spring having a stiffness k = 3 N/m and..."

In this video,I go over another dynamics problem that explores the idea of the spring force as well as dynamic movement. The key to this problem is understanding how to draw the free body diagram as well as understanding the concept of the spring force. In conjunction with newton's laws of motion, we can figure out the body's movement from point A to point C. Hopefully, this helped all those mechanical engineers out there!
--Problem Start--
A smooth 2 kg collar is attached to a spring having a stiffness k = 3 N/m and an unstretched length of 0.75 m. If the collar is released from rest at A, determine its acceleration and the normal force of the rod on the collar when y = 1 m.
--Problem End--
💰 AFFILIATE STUFF (thank you for the support!)
I am an Amazon Affiliate and by using these referral links you can support this channel.
▪️HTML & CSS Book (recommended): amzn.to/2vGYBEa
▪️Javascript & jQuery Book (recommended): amzn.to/2vGiXNM
▪️PHP Book: amzn.to/2uGQQ3O
▪️DELL XPS 15 (my laptop): amzn.to/2fJEQaQ
▪️Blue Yetti Microphone (my mic): amzn.to/2w06eb8
▪️Amazon Echo: amzn.to/2fJGKbx
▪️Amazon Echo Dot: amzn.to/2wO4ejJ
Thank you for using these links! ❤️

[@Kever1835]

Thanks! Wasn't very clear from the textbook but this explaination helped me alot!

[@Alex_Interests]

Glad to help!

[@merensow200]

Sir, The Force 'F' in 'y' direction, is it really upward direction? I suppose there is mass 2 kg hanging on the collar. Therefore it might face downward direction.

[@merensow200]

Please verify soon. I need to clear its doubt

[@Alex_Interests]

Yes, the force, F, is in the upward direction. Just imagine stretching a spring, you will feel the spring trying to resist the stretching and try to restore itself from equilibrium. Now this is true if we have a free body diagram of the collar. Now if you switch the free body diagram to the spring, the force, F, would point downward like you said due to the weight. And both free body diagrams would be correct because of Newton's 3rd Law. This is just like having a box sit on a table and drawing a free body diagram for both the box and the table. So I think your confusion is based on the "perspective" of free body diagrams; you have to choose one object and look around that object only and see what forces are acting on it. Now, for extra studying stuff. What if you let the F be downward and did the math? Would the answer still make sense? Will the math "fix" the guess of the direction of the force like in Statics? Something to think about.

[@VirtuozEd]

didnt understand how did u get 9 from normal force. How did u calculate to get this figure?

[@Alex_Interests]

I got 0.9 N. Watch 7:00 .

[@happymomentzz8887]

Hi can you please tell how to calculate initial downward velocity

[@Alex_Interests]

The problem states, "If the collar is released from rest at A...", so the initial velocity is zero. Whenever you see "at rest", you assume zero velocity.

[@happymomentzz8887]

@@Alex_Interests Thank you for the reply. I wanted to know the velocity it travelled to reach that distance downward.

[@cartonks.2492]

book example is much simpler u just mafe that complex xd