# Recent content by Qube

1. ### Normal Stress in Rods Experiencing Temperature Changes

Now here is the part where I'm sort of stumped myself: Could someone let me know if my reasoning is valid? The professor explained it during office hours and all I got out of that was that something cancels out and the answer is 0.
2. ### Proper free-body diagram for a shaft experiencing multiple torques

I don't see a direct constraint on Tmax in this problem that is given. I'm still unclear on what you mean by: The only constraint I see is on torsional shear, which is a function of Tmax.
3. ### Proper free-body diagram for a shaft experiencing multiple torques

1500-T<Tmax I'm still unclear on what you mean, sorry.
4. ### Proper free-body diagram for a shaft experiencing multiple torques

I don't understand, but I'll give it a try. Are you saying to plug 900-T, 1500-T, and 1800-T into the equation, shear=Tc/J and try to maximize the value of T?
5. ### Proper free-body diagram for a shaft experiencing multiple torques

Okay, scratch all that. I managed to figure it out by finding similar problems. Thank you for the guidance. I hope that this post of mine is error-free! We need to start by applying the right-hand rule to the applied torques, with the sign convention that a torque directed away from point E is...
6. ### Proper free-body diagram for a shaft experiencing multiple torques

Okay, I reworked the problem. I drew a torque diagram. It seems that the maximum possible value of the unknown torque, T1, is 327 Nm. From there, it seems that the internal shear stress in section CD is about 47 MPa, and the internal torque in DE causes the bar to hit its shear stress limit...
7. ### Proper free-body diagram for a shaft experiencing multiple torques

Thanks! You are right, it is J=pi*c^4/2. I will rework this problem and see if I get the right answer this time...
8. ### Proper free-body diagram for a shaft experiencing multiple torques

I wish to draw a proper free-body diagram for this shaft. However, my FBD does not agree with the solutions manual. If someone could point out where I erred, that would be great. This is what I drew: From my FBD, it is clear that the maximum torque is present in section DE of the shaft. We...
9. ### Finding the maximum height of a projectile

Can we alternatively use energy methods to solve for the height of the water?
10. ### Finding the maximum height of a projectile

I got a non-response response, so I guess I'll just chalk this up to YET another case of bottom-barrel textbook editors doing bottom-barrel work in writing questions and solutions. Book in question is Hibbeler's Dynamics, 14th edition. I used Hibbeler's Statics text last semester, and the...
11. ### Finding the maximum height of a projectile

It seems that to solve the problem as stated would actually involve finding an equation relating the angle, theta, and the height on the wall, h. And then you would take the partial derivative of height equation with respect to theta to find the extrema. I'm currently awaiting a response :).
12. ### Finding the maximum height of a projectile

That's a great question, and from my discussions and research, I was told that this assumption is incorrect in this problem. That being said, the book's solution manual makes that assumption, and so does my Dynamics professor: But it seems that even if we take this assumption as valid (which...
13. ### Finding the maximum height of a projectile

Using the equations for constant acceleration, we can write the following set of equations for this problem: We have the following known physical constraints: Solving the above system of equations and constraints with a computer algebra system: So, all the solutions I found make...
14. ### Finding the final y-position of a projectile

Thanks, so what's the takeaway here for finding the final position of a particle that lands on a hill? We have the book, which asks for "(x,-y)," and the book comes up with the "-y" displacement equation. We have a famous professor on YouTube solving for "(x,y)" and he comes up with the same...
15. ### Finding the final y-position of a projectile

Here's a much more condensed version of what I'm asking: who's correct, the book or the teacher's method? The points of impact are are in x and y. Time is "t."