Forces Definition and 1000 Threads

Homework Statement I need help with number 4. Also I am altogether unsure of this problem... if you catch any mistakes, point them out! :) Homework Equations F = ma Here are the variables I used in my attempt at the solution mx = m subscript 1, 2, or 3 ±a1 = acceleration of either mass on...

Essentially I have a spindle with a weight placed at a fixed point. There are four different weights to take into consideration, all are positioned at the same point. The results I have show what the voltage (pk-pk) output there is, therefore I can see how the out of balance varies depending...

1. Homework Statement You are pulling a 39kg box on a level floor by a rope attached to the box. The rope makes an angle of 21 degrees with the horizontal. The coefficient of kinetic frictions between the box and the floor is 0.23. Calculate the magnitude of the tension in the rope needed to...

I have a doubt regarding the definition of rotational work, which is as follows W = \int \tau_z d \theta Where \tau_z is the component of the torque parallel to the axis of rotation z. My doubt concerns the fact that, looking at this definition, it seems that any torque which has an axial...

I do not understand the reason why a conservative force always "tries" to reduce the potential energy of a system at its minimum (forgive me if I said it in a wrong way). The explanation I gave me is: since for a conservative force, from the definition of potential energy, W=-\Delta U that...

Homework Statement How would you determine whether a member is in compression or tension given the bridge with external forces below? Homework Equations None.The Attempt at a Solution I don't need help finding the forces, I need help in figuring out compression/tension. [/B]

Homework Statement A skier on a slope inclined at 4.7 degrees to the horizontal pushes on ski poles and starts down the slope. The initial speed is 2.7 m/s. The coefficient of kinetic friction between skis and snow is 0.11. Determine how far the skier will slide before coming to rest. Answer...

Homework Statement A child is pulling a wagon of mass 7.38 kg up a hill inclined at an angle of 14.3 degrees to the horizontal. The child applies a force parallel to the hill. The acceleration of the wagon is 6.45 cm/s^2 up the hill. Friction is negligible. Determine the magnitude of (a) the...

Could anyone help me with the following questions? - Why is the work done by conservative forces equivalent to the potential energy? - Why is the variation of the potential energy in such cases equals to the variation of the work function? Thanks!

Homework Statement Calculate the reaction force at A? Homework Equations ΣMb = 0 The Attempt at a Solution As there is a pin joint at B it is possible to consider the bar only from A-B. From here I applied ΣMb = 0 120 + 20*2 + Ay*4 = 0 This gives Ay = -40kn Also since there are no forces in...

Homework Statement We place a rubber on the edge of a rotating disk. What forces act on the rubber? At what angular velocity, why and in what direction will the rubber fly off the disk? Homework Equations http://images.tutorvista.com/cms/formulaimages/83/angular-speed-formula111.PNG The...

Setting a cartesian system how can i get the equation of the trajectory of an object knowing the forces acting on that object? Example: If F= GMm/r^2 and let be the sun at the center (point (0,0,0)) of the cartesian system how do i get the equation of an ellipse in this system? ( x^2/a^2 +...

Three blocks, each of mass 13 kg are on a frictionless table. A hand pushes on the left most box (A) such that the three boxes accelerate in the positive horizontal direction as shown at a rate of a = 1.4 m/s2. 1)What is the magnitude of the force on block A from the hand? 2)What is the net...

I was just scrambling and thought of rockets. So I came up with an equation for (hovering). Note: This might be totally wrong. Okay so we have a rocket with fuel with a mass of M. There is gravity acting on it so I need a force to balance things out. F - Mg = 0 F = Mg What I have learned is...

For example, why is the strong nuclear force strong enough to hole protons and neutrons together.

A trolley is moving at a constant speed down a track, with no net force acting upon it. A heavy load is dropped vertically on top of the moving trolley. What happens to the trolley's speed? a) It stays the same, b) It decreases, c) It becomes zero, d) It is impossible to say, e) It increases...

Homework Statement A projectile launcher fires a projectile horizontally from a platform which rests on a flat, icy, frictionless surface. Just after the projectile is fired and while it is moving through the launcher, the projectile has an accelleration of 25m/s^2. At the same time, the...

Homework Statement When doing force problems, you're sometimes asked to solve for the magnitude and direction of a given force acting on an object given the mass of the object, its accelleration, and the other forces acting on it. However, the force that you need to solve for could be...

Hi there, I am currently trying to work out what force I will need to pull the curtain out and in (in the system shown in the attached illustration) so that I can calculate the torque required to turn the black cylinder component and therefore find out what motor I will need. I am simply...

Homework Statement Homework Equations The Attempt at a Solution c = ([32.0 N ]^2 + [38.0 N]^2 - 2 (32.0 N)(38.0 N) cos70° ) 1/2 c = 40.5 N (is this correct?) SinA / 38.0 N = Sin110° /40.5 N (im unsure how to solve this part) A = ?? net force = 40.5 N (East ? North) I am very confused...

Like, for example, how do photons attract positively and negatively charged particles. I need some help visualizing it.

I'm trying to understand the physics of car rollovers and perhaps what can prevent them in terms of the forces that are involved. According to various diagrams I've seen, there is friction applied by the tires (with some diagrams showing a set of forces acting only on a single tire which...

Good day all: I'm having trouble deriving the forces for Lift and Drag in the attached diagram. The text I have (Fundamentals of Aerodynamics - John Anderson) states the solution to be: L = N cosα - A sinα D = N sinα + A cosα Can anyone guide me through this? I think the cofunction identity...

Homework Statement Two students push horizontally on a large, 65kg trunk. The trunk moves east with an acceleration of 2.0m/s^2. One student pushes with a force of 2.2x10^2 N[E 42 degrees S]. The force of friction acting on the trunk is 1.9x10^2N[W]. Determine the force that the other student...

Homework Statement Determine the x- and y-coordinates of a point through which the resultant of the parallel forces passes. The Attempt at a Solution The first thing I did was to find the resultant forces, which is R = 0i + 0j -125 k Then I found the moment of each axis so M = (-65(12)...

Homework Statement How do you determine the direction of tension in a force/ the direction of tension acting on an object. I'm confused. Homework Equations - The Attempt at a Solution I have no clue. Help!

Homework Statement A question came to my miind: Wouldn't everything be conserved? I know that the law of momentum conservation only applies when the system doesn't have any external forces or the net of them is equal to 0. Lets just say that someone hits the ball with a bat, He applies a force...

Homework Statement Two uniform masses of .260kg are fixed at points A and B. Find the magnitude and direction of the initial acceleration of a uniform sphere with mass 0.01kg released from rest at point P that is acted on the gravitational forces of attraction from spheres A and B. The diagram...

Homework Statement Below are attached 2 beams, A and B. I have to calculate the vertical and horizontal reactions at both supports in both questions. I have done a lot of calculations and believe I have a good understanding of what is needed to be done however my forces are not balancing for...

I do not see how (2.34) shows that forces of semi-holonomic constraints do no work in the displacements ##\delta q_k## between the varied path and the actual path. Starting from (2.31), I seem to be able to prove that such forces do do work, in contrary to what is claimed in the paragraph...

Homework Statement See photo attachment Homework EquationsThe Attempt at a Solution Ive begun by defining an x and y axis, followed by find the sum of x-components of the forces, and y-components. Followed by the magnitude of the resultant force. The only method i could think of was to find...

Hey everyone, I am currently in the middle of research for a science fiction /fantasy novel where the magic system is based on the ability of a group of people to manipulate the four fundamental forces of physics. Of these four, coming up with ways that individuals could manipulate gravity and...

Homework Statement A basin surrounding a drain has the shape of a circular cone opening upward, having everywhere an angle of 34.5° with the horizontal. A 28.5-g ice cube is set sliding around the cone without friction in a horizontal circle of radius R. (a) Find the speed the ice cube must...

Homework Statement My textbook says that internal forces have no effect on an object's motion and that external forces are required to change the motion of an object. But, we looked at an expirement where a raw egg was spun and then stopped. After being stopped, it went back to spinning...

Homework Statement A circular cylindrical barrel is half full with oil. If the diameter of the base is 8.0 m, find the net force against each end if ρo = 800 kg/m3. The cylinder is on its side. Homework Equations F=P*A P=ρgdy The Attempt at a Solution P = ρo*g*h, where h is the radius which...

Homework Statement what is the 2.1 and 0.35 refers to in the equation of (9810)(2.1)(4.2)- 9810(0.35)(0.7) -Fx = 1000(5.88)(8.4-1.401) ?? is it the width ? but , the width is not given ? Homework EquationsThe Attempt at a Solution

I used to think I understood this - big mistake! I've just watched a great classic Feynman lecture posted by another PF user (a superb way to spend 50 mins of you can spare the time) https://www.physicsforums.com/threads/i-found-the-best-teacher-of-physics.855335/ In that lecture, Feynman...

Homework Statement During a tennis volley, a ball that arrives at a player at 40 m/s is struck by the racquet and returned at 40 m/s. The other player, realizing that the ball is out of bounds, catches it in her hand. Assuming the time interval of contact is the same in both cases, compare the...

Homework Statement i don't understand the statement 1 and 2 , can someone help to explain ? for 1 , does the author mean Fh= Fv ?? for 2 , does the author mean Fv = Fh + W ? but in statement 1 , Fh already = Fv Homework EquationsThe Attempt at a Solution

1. What forces and impulse impact on a bouncing basketball? I understand that it is the gravitational force, when it falls, then the normal force when it is on the way back. Are there any additional powers? The momentum, I came to the potential energy = kinetic energy, where I got the speed...

I'm reading Goldstein's "Classical Mechanics", first chapter, and am confused about what's going on in equations of forces and work in systems of particles. For example, Goldstein calculates work done by all the forces, external and internal, in evolving the system from state ##1## to state...

Hello i am working on a small clutch cable testing machine this machine can give the lifetime of clutch cable i need some assistance to figure out how much forces i need to apply on this mechanism , and because the cable related directly in the clutch I'm asking if the force in the clutch in the...

Hello everybody, this is my first post on here. I'd like to make my entrance by asking a question that's very important to me. I would like to ask what it's like to get your University PhD in Physics paid for by the Canadian Air Forces. I've been asking a lot of people, but I thought its time to...

Homework Statement A space probe has two engines. Each generates the same amount of force when fired, and the directions of these forces can be independently adjusted. When the engines are fired simultaneously and each applies its force in the same direction, the probe, starting from rest...

Hi, I'm doing a study about tire dynamics and have some question that I can't get answers to. The first images shows the forces balances. Since we have no turqe the force has to balance ant the extensence of the T_r is obvious...

Homework Statement The point charges in the figure have the following values: q1=+2.1μC, q2=+6.3μC, q3=−0.89μC. Suppose that the magnitude of the net electrostatic force exerted on the point charge q2 in the figure is 0.57 N . Find the distance d and the direction (angle) of the net force...

Let's say I have a pen up in space in a zero g environment. And I carefully give the pen a nudge at the very tip of it. That's pretty away from the center of the mass of the pen. I know that will exert a torque and the pen will spin but I want to know whether its center of mass (along with the...

klotza submitted a new PF Insights post Secondary Forces Explored Continue reading the Original PF Insights Post.

Homework Statement A 77.0 kg patient is suspended in a raised hospital bed as shown in the figure. The wire is attached to a brace on the patient's neck and pulls parallel to the bed, and the coefficients of kinetic and static friction between the patient and the bed are 0.500 and 0.800...

Homework Statement <I will attach a diagram below> In terms of m, g and r. FInd the normal force at the top of the loop. Homework Equations ∑F = Fc = FN+Fg ∴ Fc=FN+Fg ∴FN = Fc - Fg ∴ N=mV2/r - mg The Attempt at a Solution Fc=mV2/r - mg and V2=ra and a=g ∴C=mrg/r ∴C = mg ∴mg-mg=N ∴ N=0 N. BUT...