Forces Definition and 1000 Threads

Homework Statement Hi, I was wondering if anybody has an idea how to divide the forces on this structure to get the dispacement of the node 4. 2. Formulas I would like to solve this task by superpositioning forces working on different elements of the construction. (note different EI) using...

If a toroidal ferrous core has a number of windings round it and a DC current going through them, would this magnetic core be subjected to a 'shrinking force'? To phrase it more clearly, if the toroidal core was compressible, would it actually get compressed? On the one hand, since the...

The diagram drawn below shows a lever system fixed to a point on the left with a pivot point (circle) on the line which attaches to vertical line. I have dimensions for Y and Z and the forces pulling the lever down on the right, and the force acting upwards from below. I am trying to work out...

<Moved from a technical forum. Therefore no template.>I am currently analysing the forces acting on a moving vehicle. The vehicle is mounted on a rail with wheels on both upper and lower side of the rail with a spring increasing the reaction force, and thereby the friction. The vehicle should be...

Homework Statement http://imgur.com/a/Bz6PR Homework EquationsThe Attempt at a Solution I included my attempt in the picture

Say I have two masses connected by an unstretched massless spring at some height above a planet with a strong gravitational field. Once I let go, both masses would follow geodesics in spacetime towards the center of the planet. Because the masses travel radially, the spring would compress and...

Hi everyone, I'm having a difficult time figuring out this problem. Could someone give me some pointers? I set up the equations and the free body diagrams (hopefully they're correct) ; all I have to do now is solve for F.1. Homework Statement A block of mass m is on top of a block of mass M =...

Homework Statement [moderator note: Post edited to make problem statement images visible] https://www.physicsforums.com/attachments/question-jpg.113056/ My question is when forces are resolved horizontally, why is the friction force at A not taken into account? The Attempt at a Solution...

Orbits of electrons around nucleus can never exist because it can lose energy as charges accelerate so there is never orbits of electrons. Why can't we treat gravity as forces in similar fashion.. as something that doesn't really exist. My point is. General Relativity and spacetime curvature...

Hello, First of all, I'm new to this forum and to not know whether this thread is in the right place or not. If not, feel free to replace it. I'm in my first year of university, studying industrial engineering. On a test I got the following image: The red square is a block with a specific...

Hi, I am having trouble figuring out how the forces work between two straight conductors with currents going through them. I know that when the currents go the same way, the forces are attractive, and when the currents go opposite ways, the forces are repelling. I know one has to use the right...

Homework Statement [/B] For this problem, use g = 10 N/kg. As shown in the figure above, a pulley is mounted to the ceiling of an elevator. The elevator is initially traveling with a constant velocity of 1.40 m/s, directed up. The rope (which we assume to have no mass) passing over the...

Here is all the work I have done so far (hopefully it is right). My brain somewhat shuts down when it comes to ratios.

Homework Statement A body of mass "m" is let go from on top of a surface A, where it slides down to B(without friction). From that point on, it displaces itself on an horizontal surface 5 meters away from B, where it stops at C. Being "m" a mass in kg "h" in meters and g = 10 m/s^2 The value...

I am studying momentum and I just want to check that I understand the idea correctly. Think there's a system.In this system there's two masses ##m_1## and ##m_2## moving with some velocity ##\vec v_1## and ##\vec v_2## and they exert a forces each other.Lets call the total force acting on...

Homework Statement Problem # 4:[/B] A thin semicircular rod has a total charge +Q uniformly distributed along it. A negative point charge -Q is placed as shown. A test charge +q is placed at point C. (Point C is equidistant from -Q and from all points on the rod.) http://imgur.com/AeVfddb Let...

Hello everyone, conservative forces only depend on position (cannot depend on time), i.e. ##F(x)## and are equal to the spatial derivative of the potential energy function ##U(x)##: $$F(x)= - \partial U(x)/\partial x$$ Conservative forces always have to change the kinetic energy KE and...

Homework Statement A block is placed on a inclined plane. The incline of the plane is 21° .A 24 N force is required to push the block up the incline with constant velocity. The force is applied at an angle of 15° as shown in the picture. The coefficient of kinetic friction (μk) is 0.26. What...

When a perosn is climbing up a rope with mass a ( attached to ceiling) with acceleration a how does the physics work and what forces will be applied on ceiling? I know when the rope is massless all the force gets transferred ,but now hwat will happen

Homework Statement The original question was to find the value of the angle between PA and AB. I have a certain idea regarding how to find it, but first I have to identify all forces acting on the system and their directions. So, I would be grateful if someone can explain how the frictional...

why force parallel to the axis of rotation do not make any torque.

Homework Statement I've encountered a question about electrostatic forces on vertices of an equilateral triangle and I believe that I solved it correctly but my Physics teacher has marked it as incorrect. Am I correct? Amy clue why my Physics teacher marked it wrong? This is the question and...

Homework Statement For this problem , i found that the internal force AB at point A and point B pointed in the same direction ( as shown) in my working , so , how they cancel off each other ?Since they can't cancel off each other , so they are not stable , right ? The structure is statically...

Homework EquationsThe Attempt at a Solution [/B] I was of the understanding that the slope can be calculated as mgsin20 whereas the force acting straight down through the lift is mgcos20 but the answer is mg divided by cos 20??

Homework Statement The following circuit is given. I intend to calculate the current in every resistor (every quantity except i1, i2, i3, is known). My textbook states that ℰ3-ℰ1 = (R1+R2+R3+R4+2r)*i, but I think it should be -ℰ3+ℰ1 on the left-hand side, since the current enters the negative...

How does the object slide down the surface (With friction negligible)

so a pilot is spining in a circle at a constant speed, the g forces he will feel will be the same than normal acceleration dependant on wr but now you put him inside a tube where he can move along varying the radius of the circle now the normal acceleration will be zero because he is in the...

Homework Statement The single moon of an Earth-like planet creates tides on the planet that are slowing the planet’s rotation. The planet’s rate of rotation is decreasing at a rate of 7.00 x 10-7 radians/sec/century. The mass of the planet is 6 x 1024 kg, and its diameter is 12,600 km. The...

Homework Statement The 5.7 N weight is in equilibrium under the influence of the three forces acting on it. The F force acts from above on the left at an angle of α with the horizontal. The 5.2 N force acts from above on the right at an angle of 63◦ with the horizontal. The force 5.7 N acts...

Homework Statement In my AP Physics class we need to design a loop that pulls around 4 G's. From what I understand, the diameter of the loop must be 2/5 times the initial drop. I cannot seems to get the G forces around 4. Any help? I found that the Clothoid loop reduces G forces but I can't...

Hello I have a question about the explanation given for the attached image about the balanced ladder on a wall. At the end the sentence says that, "Consequently the frictional force F at A passes through O". I am not able to understand why this is so. Can anybody please shed light on this...

Homework Statement Is it possible to find the VA , VB and VC without ' breaking ' the beam into 2 parts ? Homework EquationsThe Attempt at a Solution Here's my working , i gt Moment about A = 10(1) -VB(2) -VC(4) +5(3)(4 + (3/2) ) = 0 Hence , 92.5-2VB -4VC= 0 moment about B = VA(2) -10-VC(2)...

Homework Statement sorry, me again. The following figures show various forces acting on gliders of various masses at rest on a frictionless track. In each case, the force is applied for 30cm. The choice listing the examples in decreasing order for the increase in kinetic energy is {-4J < -2J <...

Homework Statement Homework Equations F = ma The Attempt at a Solution My value for P does not make any sense. Why is this so?

Homework Statement If the incline of the driveway is 19 ∘ from the horizontal, what must the minimum coefficient of static friction be between your shoes and the ice? Homework Equations Fs=uN The Attempt at a Solution

Tidal Forces: "It arises because the gravitational force exerted by one body on another is not constant across it". which implicitly implies that the acceleration is not constant on that body. Equivalence Principle: "weightlessness sensation occurs when one free falls in gravity" - which...

I was watching the following TED Talks video about using carbon nanotubes to build a space elevator: After the 12-13 minute point the speaker starts describing how very short carbon nanotubes can be pulled from a "nanotube forest" and spun together to create a very long thread. However the...

Homework Statement A(n) 895 N crate is being pushed across a level floor by a force of 397 N at an angle of 21◦ above the horizontal. The coefficient of kinetic friction between the crate and the floor is 0.24. The acceleration of gravity is 9.81 m/s. What is the acceleration of the box...

As far as I know, we regard the electromagnetic force, gravity, strong and weak interactions as the four fundamental forces. We know that Newton's law of gravitation does not perform as well as Einstein's general relativity. Scientists are now using energy-stress tensor to describe...

Hi, If you had a sealed round bottomed flask on some lab scales and you recorded the mass and then you removed all the air with a vacuum pump and then found the mass of the flask again would the difference between the two readings really be an estimate of the mass of the gas in the flask? The...

Hello all, You all have always kindly helped me as I remember questions I have accumulated since high school days, and have never been answered. Eventually I gave up and forgot them, but as I grow old for some odd reason these things pop back up in my mind, like old ghosts from 35 years ago...

Homework Statement "A 1.50 kg object hangs motionless from a spring with a force constant of k = 250 N/m. How far is the spring stretched from its equilibrium length?" Homework Equations F = -kx W = mg The teacher said to call the force the spring pulls up with FT. The Attempt at a Solution...

This example is written in several books, that is if you strike a ball against a wall it applies an action force on the wall and the reaction force from the wall is the reason for the ball bouncing back..Now i have a question here that when you throw the ball, you accelerate it upto some...

Homework Statement A tugboat pulls two barges down the river. The barge connected to the tugboat, carrying coal, has an inertia of 2.0 × 105 kg, and the other barge, carrying pig iron, has an inertia of 3.1 × 105 kg.The resistive force between the coal barge and the water is 8.0 × 103 N, and...

My textbook says that for a central force at the origin, the angular momentum is constant, because the derivative rxF is zero since F points radially outwards so it is in the same direction as r. Ok, but what about the angular momentum about a point other than the origin, or the angular momentum...

Homework Statement A burst of compressed air pushes a pellet out of a blowpipe. The force exerted by the air on the pellet is given by F(t)=F0e(−t/τ), where τ is called a time constant because it has units of time. What does F0 represent? Homework Equations F0 represents the maximum force...

Homework Statement System comprised blocks, a light frictionless pulley and connecting ropes (see diagram). The 9.0kg block is on a perfectly smooth horizontal table. The surfaces of the 12kg block are rough, with μk = .2 between the two blocks. If the 5.0 kg block accelerates downward when it...

Homework Statement Two forces act on a 55 kg object. One has a magnitude of 65 N directed 59 degrees clockwise from the pos. x axis. The other has magnitude 35 N at 32 o clockwise from the pos. y axis.What is the acceleration of the object? The answer is given as 1.1 m/ s squared, (I got a...

Homework Statement A 2.34-kg cart on a long, level, low-friction track is heading for a small electric fan at 0.22 m/s . The fan, which was initially off, is turned on. As the fan speeds up, the magnitude of the force it exerts on the cart is given by at2, where a = 0.0200 N/s2. What is the...

Homework Statement A 5.0-kg block suspended from a spring scale is slowly lowered onto a vertical spring. Part A: What does the scale read before the block touches the vertical spring? (answer =49.1N) Part B: If the scale reads 32 N when the bottom spring is compressed 30 mm, what is k for...