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  1. K

    Diffusion or turbulence?

    I forgot to ask last time, but why do we add turbulence? Is it a weather phenomenon we are trying to demonstrate?
  2. K

    Diffusion or turbulence?

    Ohh, thank you! Really appreciate your help!
  3. K

    Diffusion or turbulence?

    It's called DIYnamics. Here is a link to a youtube video
  4. K

    Diffusion or turbulence?

    Thank you for a great answer! :smile:
  5. K

    Diffusion or turbulence?

    <Mentor moved to Physics> My teacher talks about turbulence (2D and 3D), but I don't quite understand this. How is the turbulence different in the two buckets, and why does my teacher talk about turbulence but not diffusion? Is not diffusion the reason why the dye spreads in the water? I have...
  6. K

    What does it mean that a rigid body is in equilibrium?

    Ohh, I see, that make sense. Thank you so much both of you! :smile:
  7. K

    What does it mean that a rigid body is in equilibrium?

    So I have always been thinking that equilibrium means that an object is not moving or having constant acceleration. On a webside they said: " A rigid body is in equilibrium when it is not undergoing a change in rotational or translational motion. " To me it sounds like the object then must not...
  8. K

    Buoyancy force when a ramp is under water

    Yeah, I see that now. Thank you both for the help by the way!
  9. K

    Buoyancy force when a ramp is under water

    Hmm, I see. But if I were to use the two equations, I would have to make sure that ##\sum F_y=mg*cos(15)+T_b sin(75)-mgcos(15)=0## ? And that would make the m=408.3 kg:oops:
  10. K

    Buoyancy force when a ramp is under water

    The buoyant force is ##F_b=\frac{1000}{2400}kg*g## The effective force is ##m=1kg-##mass of water##=(1-\frac{1000}{2400})kg## But what is the importance of the effective weight in this problem? Are these equations wrong by the way
  11. K

    Buoyancy force when a ramp is under water

    I have been looking at the units but I still don't see it :confused: ##2400 kg/m^3=\frac{1kg}{V_{block}}## ##V_{block}=\frac{1}{2400}m^3## ##p_{water}=1000 kg/m^3=\frac{mass}{\frac{1}{2400}m^3}## ##mass=p_{water}*V_{water}=1000kg/m^3* \frac{1}{2400}m^3= \frac{1000}{2400}kg##
  12. K

    Buoyancy force when a ramp is under water

    Yeah, I also think it was weird that they used the word weight, because I also thought kg/m^3 is density. So I just assumed the person who wrote the problem mixed up the words. But I struggle with finding the acceleration, do you know how?
  13. K

    Buoyancy force when a ramp is under water

    Hmm, I'm sorry, but I don't understand. Why does the water displaced have the mass of 1000 kg? I thought like this ##p_{concrete}=m_{block}/V_{block}## ##V_{block}=1/2400 m^3=V_{water}## ##p_{water}=m_{water}/V_{water}## ##m_{water}=1000/2400 kg##
  14. K

    Buoyancy force when a ramp is under water

    So I have made force diagram And I think that I should find the acceleration by using these equations: ##\sum Fx=w\sin(15)-f_k-T_{x-buoyancy} ## ##\sum F_y=N+T_{y-buouancy}-w ## I know that the volume of water displaced must be ##V=\frac{1}{2400}m^3## and the mass of the water is then...
  15. K

    Help with understanding this rigid-body equilibrium problem

    Thank you so much everybody for your relplies, I really appreciate it!:smile: I will now try to solve some more problems like this with your comments in mind, and see if I understand it better now.
  16. K

    Help with understanding this rigid-body equilibrium problem

    So here are two problems I have been working with lately: I have solved both, so I don't need the help to find the answers. The thing that confusses me is which object one should choose to apply the equations above. When it comes to the first problem, we apply the equations to the pole, but...
  17. K

    When does an object have kinetic rotational energy?

    Ok, I think I got it now (or I hope so 😁). Thank you so much for everbody's help. I really appreciate it!!!
  18. K

    When does an object have kinetic rotational energy?

    Ok, I think I understand a bit more now. So for a particle, the equation would then result in a double count. But when do I know if I can treat the object as a particle or a rigid body? Because if it was a rigid body, then I would have to use ##T = T_{CM} + T_{rot}## right? I'm sorry for all the...
  19. K

    When does an object have kinetic rotational energy?

    So the rotational energy is the same as the kinetic energy in this example? But in several problems, for example when a ball dropps from a height. They wright the equation as this ##mgh= \ {1\over 2} mv^2\ + \frac{1}{2}I\omega^2 ## So I thought they where two different things?
  20. K

    When does an object have kinetic rotational energy?

    When does an object have rotational energy? Is it only if it rotates around an axis within the object? Does for example a ball attached to a string with a uniform circular movement have rotational kinetic energy?
  21. K

    Projectile-car system and momentum

    Thank you so much for the answer. I don't know either what's wrong with the solution. But it is good to know that I'm right at least. Thank you again!
  22. K

    Projectile-car system and momentum

    I have done question 1. But I'm struggling with the other one. So since the only thing I know about the rocket is the mass and the velocity, I guess I have to use momentum to solve this problem. From the first question, I found out that the x-velocity of the projectile is ##v_x=5...
  23. K

    Understanding rigid-body equilibrium problem

    Ohh, that makes sense! Thank you so much!
  24. K

    Understanding rigid-body equilibrium problem

    So I have this problem The soultion to the problem gives me this drawing But I don't understand what ##F_h## and ##F_v## is
  25. K

    Help with understanding this momentum problem

    Sorry, for not answering before now. My internet has been down the last couple of days. I understand the minus sign now. Thank you so much for your answers, I really appreciate it!
  26. K

    Help with understanding this momentum problem

    Solution on the link: https://www.slader.com/textbook/9780321675460-university-physics-13th-edition/269/exercises/12/
  27. K

    Help with acceleration -- A block on top of a block on a frictionless table

    I have tried but I still dont get it. Maybe I'm doing it wrong? So box B is affected by the weight of box A equal to ##m_A*g## and the normal force from the ground ##m_B*g## and then the pull equal to 12 N. Box A is only affected by the friction force going in opposite direction of the...
  28. K

    Help with acceleration -- A block on top of a block on a frictionless table

    I don't understand the problem. Does not block A and B make a system, so they should have the same velocity and acceleration at all time? If not, why do they have different accelerations? I don't understand this part of the problem either: "pull applied to block B equals 12.0 N, then block B has...
  29. K

    Average speed and average velocity

    Thank you guys! I think I understand it now! :smile:
  30. K

    Average speed and average velocity

    So thing that confusses me, is what is the difference regarding the calculation of speed and velocity? In think I should use the formula I wrote above to find the average velocity, but I don't understand what the formula for average speed will be then. By the way, when using the formula above...
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