1. ### Rotational Equilibrium Problem [SOLVED]

See attached file. Answer is supposed to be 61.25 N, I get 20.09 N.
2. ### Help finding the vertical component of the reaction at C

Hello everyone, For this equation, I have found Ay as 0.677kN by using Ma = 1.5kN(7m)-Ay(15.5m). To find Cy, would I be using the sum of forces to find the answer? For example Fy = Ay - F2 - F1sin55 + Cy = 0 This would then get Cy answer as 2.05kN
3. ### Chemistry Calculate DeltaH between 700K and 800K

Hi all Knowing that ##kp## is: ##k_p=\frac{pO_2.(pNO)^2}{(pNO_2)^2}## And knowing these relationships between the partial pressures, I obtained: At 700 K: ##pNO = 0.872.pNO2## ##k_p=pO_2.(0.872)^2## At 800 K: ##pNO = 2.5.pNO2## ##k_p=pO_2.(2.5)^2## Furthermore it is known that ##pNO + pNO +...

5. ### Calculate the average number of oscillators of an Einstein solid, in the grand canonical ensemble, when q>>N

$$Q_{(\alpha, \beta)} = \sum_{N=0}^{\infty} e^{\alpha N} Z_{N}(\alpha, \beta) \hspace{1cm} (3.127)$$ Where ##Q## is the grand partition function, ##Z_N## is the canonical partition function and: $$\beta = \frac{1}{kT} \hspace{1cm} \alpha = \frac{\mu}{kT} \hspace{1cm} (3.128)$$ In the case of an...
6. ### Think of a body which is at rest but not in equilibrium

When a ball is thrown upward it becomes at rest at maximum height, at this it is not in equilibrium although it is at rest. It is not at equilibrium because force of gravity is acting on it? Still I cannot find good explanation from exam point of view.I also cannot find the figure/diagram.
7. ### 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...
8. ### Chemistry Why do we say that the concentration of solids and liquids are constant?

I was introduced to the concepts like molarity, molality , mole fraction, formality, normality etc. during general chemistry and it was said that these concepts are used to measure the concentration of solutions. But as the thing called Chemical Equilibrium came I was surprised when I read "In...
9. ### I Thermodynamic equilibrium with fixed energy/entropy

If you take a system with fixed entropy S0 and let it evolve, it reachs equilibrium. Let Ueq be the energy of the system at equilibrium. Now take the same system with fixed energy U=Ueq (S is not fixed anymore), how do you know that the equilibrium reached is the same as before, that means with...
10. ### A Equilibrium point of matter and radiation density

We want to calculate the ao/a(teq) of the equilibrium point between ρm and ρr (ρm= ρr ) My book solves it this way; ρm(t) / ρr(t)= a(t) ⇒ ⇒ (ρm/ ρr)teq =1 = = (ρm/ ρr)o * a(teq)/ ao I don't understand the a(teq)/ ao part. If ρm(t)= ρο/αo3 and ρr(t)= ρο/αo4 then it should be ρm(t)/ ρr(t) =...
11. ### Normal reactions at the bases of two light supports

For equilibrium, using ##\Sigma \vec F = 0##, we get ##n_1 + n_2 = 300\; \text{N}##. Taking the system as a whole and applying ##\Sigma \vec \tau = 0## about the hinge (pin) at the top from where the load is hung, we get ##n_1 \times (0.8) \times 4 = n_2 \times (0.6) \times 3##, by taking...
12. ### Spring is stretched, then attached to a mass, what is its speed at x?

Dear all, I am back with another Spring problem. I have tried to use the insights I gained from your help last time: https://www.physicsforums.com/threads/find-v-x-of-a-mass-suspended-from-a-spring.972942/page-3#post-6190934 I figured I start with calculating the new equilibrium by ## x...
13. ### I The zeroth law of thermodynamics

let's assume I have 2 systems A and B. the surface that describes when the 2 systems are in equilibrium is given by F(a1,a1,...,b1,b2,...) = 0. assuming we can write this surface as A(a1,a2,..)=B(b1,b2,....) why do A and B describes the temperature function of the systems? in class, we...
14. ### Mass hanging from a 2-pulley system

Homework Statement I have a question about the pulley problem in the attachment. Homework Equations This question can be answered using equilibrium of forces, namely Fx = 0 and Fy = 0. The Attempt at a Solution The answer key states that for the sum of the x-components, we should use the...
15. ### Free body diagram problem

Hello everyone. I find the following problem confusing. A board sandwiched between two boards in the figure below weighs 95.5N. If friction exists between the middle and the compressing boards, draw the free body diagram of the middle board. Below I attached the diagram found in the solution...
16. ### Chemistry Equilibrium Partial Pressures

Homework Statement Kc = 4.15 x 10-2 at 356°C for PCl5(g) ↔ PCl3(g) + Cl2(g). A closed 2.00 L vessel initially contians 0.100 mol PCl5. Calculate the total pressure in the vessel (in atm to 2 decimal places) at 356°C when equilibrium is achieved. Homework Equations PV=nRT Kp= Kc(RT)^change in...
17. ### The concentration of B at equilibrium

Homework Statement For the reaction given below, 2.00 moles of A and 3.00 moles of B are placed in a 6.00L container. A(g) + 2B(g) --> C(g) At equilibrium, the concentration of A is 0.246 mol/L. What is the concentration of B at equilibrium? Homework Equations for aA+bB-->cC, K = [C]^c/([A]^a[...
18. ### Can 3 forces of 9N, 4N, and 6N be in equilibrium?

Homework Statement A mass of 3kg is acted upon by three forces of 4.0 N, 6.0N, and 9.0N and is in equilibrium. The 9N force is suddenly removed. Determine the acceleration of the mass. Homework Equations F=ma. The Attempt at a Solution My main problem with this question is that I cannot think...
19. ### Resolving forces: Mass on a string

Homework Statement A mass of 50 grams hangs in equilibrium on a string. The mass is pulled aside and upwards by a force of 0.3N which makes an angle of 30° with the horizontal. Find the angle that the string makes with the vertical and the tension in the string. Homework Equations Body is in...
20. ### Calculating concenteration at equilibrium

Homework Statement 0.1mole of N2O4 (g) was sealed In a tube under one atmospheric conditions at 25°C.Calculate the number of moles of NO2(g) present if the equilibrium N204(g) --->2NO2(g) (Kp=0.14) is reached after some time Homework Equations K=[NO2]^2/[N2O4] 3. The...
21. ### B Equilibrium - Scalar or Vector?

1 Is Equilibrium a Scalar or Vector quantity? 2 What is the unit of Equilibrium? Thanks & Regards, Prashant S Akerkar
22. ### Plasma Pinch Pressure

Homework Statement Prove that in an MHD equilibrium state in a pinch with flux and Bθ(r) and Bz(r), the equation for pressure is; d/dr(P + B2/8π) + Bθ2/4πr - ρ( u2θ/r)= 0 B is the total Magnetic field, uθ(r) the velocity of plasma, ρ= density, and solving in a (r,θ,z) system Homework...
23. ### B My Second Post: Change in Magnitude of Normal Force?

Hello, Let us imagine a solid immersed in a liquid in a container such that the density of the liquid is less than the density of the solid. This means that the solid must sink. Let us study the solid when it reaches the bottom surface and is now at rest. The forces acting on the solid when it...
24. ### FBD of an aerogenerator (Windmill)

Homework Statement Good afternoon, I hope someone could help me with this problem, it is killing my head. I have an aerogenerator, I already find the torque excerted by the air (75.8N) and the force transmitted by the gear (1010.6N). The problem comes when I try to draw the free body diagram to...
25. ### I Quick clamp wedge/friction lock calculation

I am currently working on designing a linear brake/lock for a completely different purpose but it will be based on the same principle as in a quick clamp shown below. Before building a prototype I do want to make some rough calculations to check dimensions, angles etc. etc. However, I am for...
26. ### For a solution that contains 0.10 M HCN and 0.10 M NaCN, whi

Homework Statement >For a solution that contains 0.10 M HCN and 0.10 M NaCN, which statement is false? A) This is an example of the common ion effect. B) The [H+] is larger than it would be if only the HCN was in solution. C) the [H+] is equal to $K_a$ D) Addition of more NaCN will shift...
27. ### Finding a maximum force in a beam type system before failure

Homework Statement See attached photo Homework Equations Stress = F/A Area = pi d^3 / 4 Sum F h = 0, Sum F v = 0, Sum M = 0 The Attempt at a Solution Hey everyone, after reading the question a number of times and not knowing for certain where to start, I figured because the stress and area...
28. ### Conceptual question about frictional force and equilibrium

A uniform beam of length L and mass m is inclined at an angle θ to the horizontal. Its upper end is connected to a wall by a rope, and its lower end rests on a rough, horizontal surface. The coefficient of static friction between the beam and surface is μs. Assume that the angle θ is such that...
29. ### I Universe equilibration

I have a question regarding the process of getting towards equilibrium in our universe. If we imagine a causal patch with our planet at the centre, every planet will redshift away from us an after a while the planet itself will disintegrate, let's call this process the decay of Earth. Eventually...
30. M

### Find the tension in the cable and the force the ramp exerts on the tires

Homework Statement A 5000 kg car rests on a 32° slanted ramp attached to a trailer. Only a cable running from the trailer to the car prevents the car from rolling off the ramp (the car's transmission is in neutral and its brakes are off). Find the tension in the cable and the force that the...