Forces Definition and 1000 Threads

Homework Statement Lets say I have two objects, with the same mass, m, and charge (+q), with a distance r between them. They repel each other due to electrical force, but they are attracted due to gravitational force. My questions is: What should be their mass m such that they feel no net...

This is most likely dead simple but my brain has shut down for the day! Lets say a Hydraulic Jack is placed in a square steel frame so once the jack is operated it acts upon the top and bottom rails which are held in place by the two side rails... The jack is pumped up to say 10 tonnes - does...

Not the best at physics but trying to understand the standard model. So can someone please tell me if this is right or not and if not, can you explain me why? Higgs bosons reacts with everything that has mass. Electromagnetic force reacts with everything that has charge. Weak force reacts with...

Hi again, I find this topic particularly fascinating. Can anyone point me to a good article/or provide a summary which explains how the 4 fundamental forces work? If possible not wikipedia, I find wikipedia very jargon-y. I did a search and found some rubbish I posted a couple of years back...

Homework Statement We have two balls connected by a string. Let's assume string has no mass. One ball is on the table, spinning in circle at a constant speed, connected by string to a hole with another ball, hanging. Here is picture. https://imgur.com/a/TtEjK Homework Equations Finding...

Could someone please explain to me how the moment generated by P is calculated by PLsin@. I understand the length I just can't figure out how it is Psin@. I believe the moment acts opposite to force F but when I build my triangle for trigonometry I'm getting it wrong?

In the arm-wrestling, when the hand A prevails on the hand B, the force of A on B is greater than that of B on A?

<< Thread moved to the schoolwork forums from the technical forums, so no Homework Template is shown >> The problem is a modified version of two basic block problems. This is my work so far, but I end up with two equations for acceleration from m1 and m2, I don't understand how to use both...

Homework Statement A particle of mass m is moving in a circular path of constant radius r such that its centripetal acceleration a varies with time t as a = k2rt2, where k is a constant. Show that the power delivered to the particle by the forces acting on it is mk4r2t5/3. [/B] I have solved...

I’m trying to calculate how hard someone throws a ball. I know that F=ma, but the only force acting on a ball is the force of gravity and so the equation simply cancels out.

Hello, I am trying to analyze the forces on a chain and sprocket system. Specifically the force on each tooth that is engaged with the chain rollers on a driven sprocket. Here are a couple links on the topic, however niether of which provide a derivation or sample calcs on how they got their...

Everybody says when going around a corner on a motorcycle and leaning, you feel the g forces vertically (like pushing down on your spine) as opposed to horizontally when cornering in a car. I can't understand how that can be the case, if the rider corners at 45 degrees, the gravitational force...

Hi everyone. Our mechanics professor warned us that in the mid-term exam some students reached the right answer on some questions but their method was wrong. For this reason sometimes I'm worried when I reach the correct answer but the way I did it is different from the solution guide. And I...

Homework Statement For a project we have to find a movie scene and calculate using any variables we can find. I am using Back to the Future and want to calculate the distance the DeLorean travels in one of the first scenes when they're first using it. I'd also like to find the acceleration from...

When I read pages or look at calculators for car suspensions it seems they have things wrong. They seem to consider both the upper and lower arms as a straight line intersection where the tire contact patch effectively "pushes" through the intersect point. I'm trying to understand the forces...

Homework Statement A person of mass M is walking across the ground carrying a heavy bucket of water of mass m on top of their head. Which of the following forces is not acting on the person? a) The gravitational force on the person Mg acting downward b) The normal force from the ground acting...

I volunteered to help tutor students in a nearby high school in math and science. I got two seniors from an AP Physics class. I'm doing OK with most of the problems, but it's been almost 50 years since my last physics class, so I'm more than a little rusty in some details. I'm hoping I can get...

Hi everyone, This is not really a homework question per se since it's not an assignment. Basically, our physics professor gave us a 100+ page syllabus filled with example questions and solutions and I am practicing with them by doing them one after the other. This one question I'm having...

Are conservative forces always taken as internal forces?

The questions States. A uniform plank of weight 120N rests on two stools. a weight of 80N is placed on the plank, midway between the stools calculate A) the force acting on stool A B) the force acting on stool B (Cant add a picture for some reason.) Plank over length = 4.0m from left hand...

Homework Statement The work done by an external force to move a -8.0 uC charge from point a to point b is 25*10^-4 Joules. If the charge was started from rest and had 5.2 * 10^-4 Joules of kinetic energy when it reached point b, what must be the potential difference between a and b? Homework...

Homework Statement I am referring to this thread and question: https://www.physicsforums.com/threads/rotation-of-a-spool-about-rough-ground.295666/ Here is the problem, restated: Homework Equations ##\tau_{net} = I\alpha## ##\tau = Frsin(\theta)## ##F_{net} = Ma_{cm}## ##\alpha = a_{cm} /...

Assume a person is at space, and assume there's no friction or gravitational force in that space. The person has a bow and arrow. He stretches the arrow on the bow, and then shots the arrow out in the space. Since there are no friction and gravitational force in that space, the arrow will have...

Homework Statement How do I draw all forces on a stone sinking in water? And what are the names of the forces? And will the stone reach terminal velocity and be sinking in constant velocity? Homework Equations In some websites they just draw buoyant force and gravity force. But in other...

Well, we all know that normal force is the force that keeps things from falling to the center of the earth, right? Well, that should apply to horizontal surfaces such as the ground. But does normal force work for vertical and diagonal forces such as a wall, too?

I'm reading my coursework (Gen Chem) and I just have a question that hasn't really been answered. So, when you have a collection of atoms taking visible form, like with Sulfur for example, the atoms are held together simply because they're close together, which I think is the principle of VDW...

I am having trouble recognizing reaction forces. for example, problem 6.8 on pin C there is no y component, the argument there was because there is no vertical member attached to C. That is understandable, but if we follow the same logic then there should not be an x component on pin A in...

Sooooo yeah... My question is something very basic: Internal Forces vs External Forces. From my knowledge, Internal forces does not change the total mechanical energy while external does. But than why is gravity an internal force while normal force is external? Is there any other ways of...

Homework Statement For the apparatus in the figure, what is the minimum value of the coefficient of static friction between the block (m3) and the table that would keep the system at rest if m1 = 0.10 kg, m2 = 0.20 kg, and m3 = 0.30 kg? (Assume ideal conditions for the string and pulleys.)...

I understand intuitively that an automobile is set in motion because the wheels apply a force on the road in a backwards direction. Using Newton's 3rd law, the car gets propelled because the road applies a reaction force in the opposite direction. Before starting to ask my full question, I...

Homework Statement A sled of mass m is given a kick on a frozen pond. The kick imparts to it an initial speed of 2.20 m/s. The coefficient of kinetic friction between sled and ice is 0.150. Use energy considerations to find the distance the sled moves before it stops Homework Equations...

Homework Statement Homework Equations Friction Force = normal force * static coefficient for friction Fnet = ma The Attempt at a Solution So i drew the free-body diagrams for both the objects...[/B] Im trying to figure out the tension in the 2nd free body diagram and i know that it's...

There is a random person falling from the sky. He remembers that he has a jetpack. Unfortunately, his jetpack is weak and is only able to provide upward force equivalent to Fg. WILL HE?SHE STAY AFLOAT OR WILL HE?SHE CRASH INTO THE GROUND? What acceleration will he/she hit the ground?

Homework Statement Homework Equations Torque = r x F The Attempt at a Solution I expect the door to fall.

If you have uniform magnetic field, would something like a halbach array which has a non symmetrical magnetic field experience a net force? If not, is there any way to shield one side of a magnet so that it would experience a net force? On a similar note, if you wound a wire around a sphere in...

Hi everyone, I am new to this forum, and I'm having a hard time understanding Newton's third law and collisions, first of all I want to say that it is not homework and that I do know the basics of physics, vectors, energy, work, and momentum I also know and understand Newton's first and second...

Homework Statement Calculate the braking distance for a car traveling at a speed of 35.0m/s down a hill at an angle of 10.0 degrees relative to the horizontal. Homework Equations F=ma v=u + 2as[/B] The Attempt at a Solution The teacher briefly explained this in class saying that the total...

In a physics test in a Norwegian website of a school book, it says following: True or false? (1) According to Newton's 3rd Law, the weight of a book that is on a table is just as big, but opposite the force on the book from the table (normal force). FALSE. (2) According to Newton's 1st Law...

The question that puzzled me during lecture! : A block is pushed so that it moves distance L up a ramp (incline angle q ) at constant speed. If there is friction, the magnitude of the work done on the block by friction…(ramp is up and leftwards) A. is mgsinqL. B. is less...

hello everyone I have spinning droplet. I want to calculate the effect of centrifugal force on each cell of the droplet. If I use F= Mass * angular velocity square * radius That gave big number and it is like the whole droplet rotation around that radius. It's looks easy but I really stuck...

Good Afternoon Is it correct to calculate the force of a point charge by relating the force to the kinetic energy and this with its derivative? I have the graphic V/r (Velocity Vs Space), want to calculate force, relate work with force in this way: W=ΔEk, in my case the kinetic energy initial is...

I found a problem and I'm having one question, it goes like this: A box of 5 kg is being dragged across the floor with a horizontal force of 40 N. If it starts at rest and it begins to accelerate at 3 m/s2 (constant acceleration), find: A) The coefficient of kinetic friction B) Supposing that...

1. A plane is flying at 80m/s [n] in level flight. Draw a freebody diagram and state whether forces are balanced or unbalanced. -i wasn't sure what to draw :/

Homework Statement https://isaacphysics.org/questions/gcse_ch2_13_q10 https://www.physicsforums.com/attachments/213735 https://i.imgur.com/WnZkt83.jpg The thrust generated by a rocket engine is equal to the mass of propellant burnt each second multiplied by the exhaust velocity of the gas...

Homework Statement A rocket, weighing 43,600N, has an engine that provides an upward force of 120,000N. It reaches a maximum speed of 860 m/s. For how much time must the engine burn during launch in order to reach this speed? Homework Equations p=m*Δv i=F*t The Attempt at a Solution I started...

1. Homework Statement You have two masses moving across a frictionless surface, yet there is friction between the two masses. Mass 2 is on top of Mass 1 A force is applied to m1 which causes It to accelerate at 6 m/s2 and the friction between the two masses causes m2 to accelerate at 4 m/s2...

Two small blocks, each of mass m, are connected by a string of constant length 4h and negligible mass. Block A is placed on a very rough tabletop as shown below, and block B hangs over the edge of the table. The tabletop is a distance 2h above the floor. Block A is then released from rest at a...

Hi all In respect to a simple gear system, two cogs are linked together, Cog A and Cog B. You apply a force to cog A, and cog A transmits this force to cog B through contact of the teeth on each cog (third law pair?) If cog A pushes on cog B, does cog B not push back on cog A? Does this not...

Homework Statement I am just going over my class notes and I just wanted to clear up a few concepts regarding forces and free-body diagrams -- I'm either missing some forces or adding one too many: Identify the forces acting on objects in each of the following situations and draw a free-body...

If the front left wheel of a car traveling at approximately 60km/h impacted with a small concrete step, would any significant amount of force be applied upwards on the car? How would you calculate this force? I'm assuming that to lift a car into the air the force applied upwards on the car would...