1. L

### DIY Simple analog engine dynamometer -- How to do it?

Hi, I have to measure the HP of a small engine at the crankshaft. The only usable things are. A dinamometer A brake disk An rpm meter The brake caliper is floating so when we apply de load it pull the dinamometer. The rpm meter show the revolution during the load apply. It can works? How I...
2. ### Engineering Moment of a force about point O

G'day. I have a problem with my statics work, i understand its probably quite simple but im having trouble in my understanding. Essentially problems make more sense to me by using the component method, although in saying that i understand this problem would be quite a lot more simple were i to...
3. ### Mechanics: A bowling ball is thrown and rolls with slipping

Summary:: A bowling ball is thrown on a bowling lane with the coefficient of friction ##\mu## with an initial velocity of ##v_0## and no rotation. After hitting the ground, it starts rolling with slipping. After how much time after hitting the lane will the ball stop slipping? What will be its...
4. ### I Confusion About Rotational Motion

I watched a video that showed how to calculate the center of gravity of a horizontal bar suspended from two wires, one attached to each end. Each wire was then attached to a vertical wall. The angle each wire made with the wall it was attached to was given. They treated it as an a example of...
5. ### Automotive Vehicle Parking Brake Test on a Slope [How Convert to a Flat Ground test?]

Vehicle Mass : 3 tonnes Manufacturer's instruction is to test vehicle's parking brake effectiveness is to engage parking brake on 30.96 degrees slope. If it holds, it is effective. I do not have 30.96 degrees slope & I want to replicate the same test on flat ground. I was thinking of...
6. ### I Moment of inertia where mass and torque are at a different positions

The formula for moment of inertia is: I=mr^2 A common derivation for this is: 1. F=ma 2. τ=rma 3. τ=rmrα = r^2 mα This is a rotational version of Newton’s second law, where torque replaces force, moment of inertia replaces mass, and angular acceleration replaces tangential acceleration...
7. ### Question on torque balancing

So I tried using force balancing. I have attached files of my solution in my notebook Torque balancing about O which gives me equation 1 And I used property of triangle, for equation 2 But i can't seem to get the right answer Also, I was wondering if it could be done by concept of virtual work.
8. ### Determining moment (or torque) around a certain point on a wrench

Here's a diagram of the problem. There are 3 possible solutions: 163 in-lb clockwise, 163 in-lb counterclockwise, 82.7 clockwise or none of them. After attempting the problem the closest I got to was 82.7 but that was wrong so I'm still stuck.
9. ### Torque on a circular current loop

Can anyone please tell me why the torque on a circular current loop can be calculated by the equation below? In other words, what is the intuition for the formula? Thank you. (I modified my question to a particular case) $$\vec{\tau} = I \vec{A} \times \vec{B}$$
10. ### B What force will be felt by ##B## when a rod is rotated?

We have a rod ##AB## of mass ##m##, a force (perpendicular to AB) is applied at ##A##. I want to know how much force will ##B## going to feel? When ##F_1## is applied at ##A## rod will rotate about its COM (which lies at the Center) and hence the point ##B## will also move (a little downwards...
11. ### Calculate the output power for da Vinci's tank mechanism

Hello everyone. I'm working on 3D animation about da Vinci tank and why it doesn't work. Please help me find out how to compute: 1: how many men need to move this machine 2: what power on wheel can produce different number of man, like 1, 2, 4, 8.. vehicle mass = 8t men strength = 60kg lever...
12. ### I Integral for the calculation of torque

Hello, I found an integral to calculate the torque from the applied torsional shear stress, and I didn't find an explanation of how this integral is deviated. Where does it come from? Could someone explain? T = ∫τ⋅r⋅dA = ∫τ⋅2πr⋅dr, where T is the torque and τ the shear stress. Thanks a lot!
13. ### Analytical mathematical modeling of the torque caused by the laundry

Hello my dear physicists, I'm trying to model the varied generated (needed)Torque to rotate a washing machine Drum during a Washing Process so i assumed that the Model has as Input the target vilocity and as an Output the new needed torque to rotate the Drum(to be as a input for the motor...

If i'm to choose a motor to suit a vertical load (torque)-see the attached picture for more illustration-. What is the criteria should i follow? After i have done the math for the weight of the object to be rotated, the torque to rotate the load is to be horizontal, and i only have the weight...
15. ### The torque (and stalling torque) of a servo motor

I'm using a servo to lift a pen. The pen and a bit of mechanism weights 35g. The servo I use to bring the pen up and down claims to have a torsional moment of 1.5kg/cm. Sometimes they call it torque in the specs. But surely that does not mean they are claiming that if I hung a 1.5kg weight a...
16. ### I Angular Momentum Vector and Torque Vector

In studying gyroscopic progression, the angular momentum vector is added to the torque vector. As intuitively these two vectors seem to be qualitatively quite different, how do we know that both vectors are in the same vector field and that they can be manipulated using the rules of vector...
17. ### Torque of a simple yoyo

total moment of inertia= (1/2) (0.098kg) ( 0.144m)^2 + (1/2) (0.098kg) ( 0.144m)^2 + (1/2) (0.016kg) (0.01m)^2 total moment of inertia= 2.03*10^(-3) kgm^2 torque= 5.2N * (0.144m) = 0.75N*m thus: 0.75N*m= 2.03*10^(-3) kgm^2 * angular acceleration angular acceleration = 368.8 rad/s^2 Is...
18. ### Torque on a circular disk

moment of inertia= [(1/2)(1.1kg)(0.96)^2+ (1.1kg) (0.75*0.96)^2]= 1.08 kg*m^2 θ=9.8 degrees= 0.17 rad torque= (mass*gravity) * radius * sin(theta) radius= 0.17rad * 0.96m = 0.16m torque= (1.1kg*9.8m/s^2) * 0.16m * sin(0.17rad) = 0.29 N*m torque = inertia * angular acceleration 0.29N*m=...
19. ### Static equilibrium of a bar attached to a hinge

item Fx Fy torque(z) rod 0 -mg -mg* (3/2) Fred 0 -Mg (-Mg) * (3/2) hinge -hx hy 0 wire F* cos(theta) F* sin(theta) 3*F* sin(theta) total 0 0 0 theta= tan^(-1) (2/3) = 33.7 degree 3*F* sin(theta) = (8*9.8)* (3/2) + (53*9.8) * (3/2) F= 538.7N tension is 538.7N
20. ### Why is the wedge force positive?

As per (b) in the above image, or easily solved with t=rFsin(theta), the perpendicular force is 260N. When inputting that value into the equation for torque, the value for torque is 520Nm, as per t=2.00*300*sin60. Because the wedge prevents the door from moving, the torque on/at the doorknob...
21. ### Rotation of a pyramid

torque=Force*radius*sin(theta) center of mass x direction = ( 0(6 x 10^9 kg)+ (118m)(6 x 10^9 kg)+ (236m)(6 x 10^9 kg) )/(3(6 x 10^9 kg)) = 118m center of mass y direction = ( 0(6 x 10^9 kg)+ (140m)(6 x 10^9 kg)+ (0)(6 x 10^9 kg) )/(3(6 x 10^9 kg)) = 46.7 m radius = (118^2 + 46.7^2)^(1/2) =...
22. ### Rotational torque and kinematics of a rod

moment of inertia = (1/3) (2.1kg) (1.2m)^2 = 1.0 kgm^2 center of mass= (0.6i, 0j) magnitude of the gravitational torque=9.8m/s^2*2.1kg*0.6m= 12.34N*m position of the new center of mass now : x direction = cos(20)*0.6m=0.56m y direction= -sin(20) * 0.6m = -0.2m change in gravitational...
23. ### Torque of a flat disk

Since torque= |force||radius|sin(theta) : î = |71E6||5000m|sin(30)= 177.5E9 N*m ĵ = |0||5000m|sin(30) = 0 k̂ = |-158E6||5000m|sin(30)= 395 N*m
24. ### Moment of inertia of a tire

I=(1/2)(6kg)(0.4^2 + 0.52^2) = 1.29 kg*m^2 initial: 34 mph= 15.2m/s 15.2m/s = (ω) (0.52m) ω= 29.2 rad/s after: 19 mph = 8.5m/s 8.5m/s = ω(0.52m) ω= 16.3 rad/s acceleration = (16.3 rad/s - 29.2 rad/s) / 5s= -2.58 rad/s^2 torque= |-2.58 rad/s^2 |(1.29 kg*m^2 ) = 3.3 N*m I am confused...
25. ### Torque and inertia of a wooden rod

∫ λ(x)=0.2 kg/m + 0.061(x/L)^2 kg/m = 0.2(x) + (0.061/3) (x^3) /(1/L^2) mass of rod = 0.2+ (0.061/3) =0.22 kg inertia of rod through nail = (1/3) (mass) (L)^2 inertia of rod through nail = (1/3) (0.22kg) (1m)^2 = 0.073 kg*m^2 torque magnitude = (53N) (0.5m) = 26.5N*m angular...
26. ### Torque and inertia of a space object

I= 524kg * 6m^2 = 18.86E3kg*m^2 KE=(1/2) (18.86E3kg*m^2) (0.16 rad/s )^2= 241.5 J torque= 0.25* 57N* (6m)=85.5 N*m
27. ### Torque generated by water flow

I know that I have to calculate force that is generated by water. However, I do it wrong way. ## A = \pi r^2 ## ## v = \frac Q A = \frac Q {\pi r^2}## ## F = P t = mvt = ....???? ## - have problem with mass. and is it even correct way? if I can calculate F - its easy afterwards... ##\tau = F...
28. ### Show that the flywheel inside the train counteracts lean in a curve

Summary: Consider a train carriage rolling along a curve that forms a left turn on the track. The carriage speed is directed along the y axis (into the plane of the paper) in the figure. The trolley will have a tendency to curl in the curve in the specified direction. A flywheel is inserted...

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30. ### Does friction torque in speeding up = speeding down?

On speeding up: τload - τfriction = Iαup On speeding down: τfriction = Iαdown If i substitute τfriction from speeding down to speeding up equation, i get moment of inertia: I = (τload)/(αup+αdown) But, is this allowed? Does friction torque in speeding up is equal to friction torque in...