# What is Physics homework: Definition and 298 Discussions

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1. ### How to Solve Dynamics Exercise Involving Force Representation?

This is the exercise: Please help me ( question 4 and 5). Here is my effort: First, I represented the forces on both objects. Then, i found F⁰ = 5N (question 1) After that, (question 2) + (question 3) I hope it's even correct.
2. ### Maxwell Stress components of the energy-stress-momentum tensor

Question: Solution: I need help with the last part. I think my numerical factors are incorrect, even if I add the last term it will get worse. What have I done wrong, or is there a better way to deal with this?
3. ### Physics homework help needed -- A mass sliding down a ramp with friction

When mass M is at the position shown, it is sliding down the inclined part of a slide at a speed of 2.19 m/s. The mass stops a distance S2 = 2.1 m along the level part of the slide. The distance S1 = 1.18 m and the angle θ = 28.10°. Calculate the coefficient of kinetic friction for the mass on...

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5. ### Recommendations for Tablets/Programs for doing Physics Homework?

Greetings! I'm a 4th year physics undergrad looking for a program/tablet that I can write/type equations into and type (or dictate!) sentences into for clarification. I have Word but the equation editor is clunky. I also tutor so being able to screenshare a large area in Zoom and easily...
6. ### Year 10 physics homework problem

I got this as homework and I am not sure how to attempt it
7. ### Intro Physics homework help - distance and velocity

I have tried this problem over 4 times and keep getting the exact same answer, which is incorrect. Could someone please help by pointing out what I did wrong, or letting me know if I am actually on the completely wrong path? Thanks! Have a wonderful day :)
8. ### Energy loss of damped oscillator

yeah, I don't even know how to start
9. ### Physics Homework Question on terminal velocity and weight

Below I've attached the question - I don't know why this question is so difficult, perhaps I missed a lesson or such, however I've Benn working at it for ages and got nowhere...
10. ### Question regarding the Pressure of a gas flowing from a cylinder into balloons

P1V1=P2V2 (2.5x10^7x4x10^4)/1.85x10^5 , V2 = 5.41x10^6 cm^3 5.41x10^6=4x10^4+7.24x10^3 N N= 741
11. ### Mastering Physics Homework about Magnetic field

Magnetic fields are sometimes measured by balancing magnetic forces against known mechanical forces. Your task is to measure the strength of a horizontal magnetic field using a 12-cm-long rigid metal rod that hangs from two nonmagnetic springs, one at each end, with spring constants 1.3 N/m ...
12. ### Physics Homework about using Electricity to Heat Flowing Water

This is the question: You want to make an electric instantaneous water heater in which 5.0 liters of water flows past a resistance per minute and heats water from 10.0 ° C to 45.0 ° C. Calculate the magnitude of the resistance to use and the amperage. The flow-through is connected to 230V So...
13. ### Vectors physics homework -- Addition of two vector forces

Trying to solve it
14. ### Solving Symbolically: Height of Cliff with No Air Resistance

Homework Statement You are climbing in the High Sierra when you suddenly find yourself at the edge of a fogshrouded cliff. To find the height of this cliff, you drop a rock from the top; a time T later you hear the sound of the rock hitting the ground at the foot of the cliff. a. If you ignore...
15. ### How to get better at theoretical homework problems

I’m having lots of trouble in my honors physics class with the theoretical homework problems that are assigned. The entire concept of learning to solve things theoretically, and then applying it is brand new to me. I’m decent at figuring out the applied problems, but pure theory stumps me. I...
16. ### Physics homework help regarding energy and friction

Homework Statement The maximum power output of a car of mass 500kg is 75kW. Up a hill of angle 11.534, its maximum (constant) speed achievable with this power is 30m/s. What is the energy dissipated by frictional forces every second, and what must the frictional force be? Homework Equations...
17. ### Physics Homework -- block pressed against a wall is sliding....

Hey! I've been trying to figure out these two problems but can't seem to get the right answer. Was wondering if someone could help me out? 1. A block is pressed against a vertical wall by a force F, as the drawing shows. This force can either push the block upward at a constant velocity or...
18. ### Electric Fields and Electric forces help

Homework Statement This is the question Structure opposite comprises 5 ions each of which has lost one electron. The sides of the square formed by the 4 outer ions are of length 0.2nm Ion E is at the midpoint 1.What is the force on A due to ion A?Homework Equations I'd imagine: F= kq / r^2...
19. ### Using a CCD camera to solve physics problems

(Sorry for Length) 1. Homework Statement You have decided to use a CCD camera to check if a 16th magnitude quasar is variable. You can presume that all of the light of your quasar falls on one pixel. You know that a star with a magnitude of 0 would deliver 1 × 10^9 photons/second to one pixel...
20. ### Physics Homework Help of converting to years (astronomy q)

A star is 3.7 x 104 ly (light-years) from the center of its galaxy and is moving in a circle around that center at a speed of 170 km/s. (a) How long does it take the star to make one revolution about the galactic center? (b) How many revolutions has the star completed since it was formed about...
21. ### Why is F=ma? (Physics homework)

I'm taking an AP physics course on the edx.org platform and I arrived today at the "Forces" Unit. One of the fundamental properties of force that it's equal to acceleration times mass, but I, as a curious stubborn nerd, always look for the "why's", so I thought to myself "why it's not equal to...
22. ### Understanding Circular Motion: The Role of Centripetal Acceleration

<Moderator's note: Removed template prior to moving it from Homework.> I am looking at centripetal acceleration, and I know that even at a constant speed the object is acceleration because its velocity is changing. But I don't understand how it is changing, like when is it negative and when is...
23. ### Scuba Diver Sees Bird: Refraction Problem Explained

1. The problem statement, all variables, and given/known data A scuba diver is underwater. She looks up and sees a bird flying in the sky. Compared to its actual distance, the bird appears to be... 1. Closer 2. At actual distance 3. Further Homework Equations n1sin(θ1)=n2sin(θ2) The Attempt at...
24. ### Solving Worked Problems: Understanding How to Get the Answer | Help Needed!

This is a worked problem, so they're just basically giving examples on how you would solve this type of problem. My issue is... how did they get 2.86s? Please someone help this has been driving me crazy.
25. ### Open Tube Resonance: Fundamental Frequency

Homework Statement A long tube that is open at both ends is used to construct a musical instrument. The sound waves that enter the tube are generated by a taut wire with a tension of 600 N and a linear mass density of 0.031 kg/m. If the length of the tube is 2.4 m and a hole is cut in the side...
26. ### Friction of rubber box on concrete floor

Homework Statement A 10 kg rubber box is resting on a concrete floor. A force of 200 N is then applied to this box in a horizontal direction. What is the magnitude of the friction force on the box? Homework Equations This is a question about applying Newton's laws so Fsmax = μs η and η = mg...
27. ### Calculating Maximum Height of an Arrow with Loss of Mechanical Energy

Homework Statement A 125 - G arrow is shot vertically upwards with a Vi of 28/ms. Assuming a 20% loss in Mechanical Energy while ascending, what maximum height above the position it was shot does it reach? Homework Equations Vi= 28m/s Vf= O m/s D= ? a= -9.8 m/s Vf^2= Vi^2 + 2aD Eg = mgh Ek =...
28. ### How to Calculate Energy Change for Lifting an Object on Earth and the Moon?

Homework Statement A person performs 6.1 J of work to lift an object without acceleration to a particular height on Earth. Write an equation describing that energy change and analyze it to determine how different the energy would be required to lift the same object to the same height on the...
29. ### Physics Homework: A bead on wire

Homework Statement A bead slides on a wire, which is in a vertical plane, as shown in the diagram. Gravity acts in the -y direction. The bead starts at A, moving to the right with an initial velocity v. The wire is frictionless between A and D and between F and G, but there is friction between...
30. ### High School Level Physics Homework

Homework Statement A highway is to be built between two towns, one of which lies 35.0km south and 72.0km west of the other. What is the shortest length of highway that can be built between the two towns, and at what angle would this highway be directed with respect to due west. Homework...
31. ### Electric Fields (Uniformly Charged Plates)

Homework Statement In the figure two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have excess surface charge densities of opposite signs and magnitude 7.76 × 10-22 C/m2. What is the magnitude of the electric field at points (a) to the left of...
32. ### Solving Physics Homework: Power Output of Heater

Homework Statement Homework Equations relevant equations listed with each question The Attempt at a Solution a) to solve for the power output of the heater, i used the following equation: Power = Energy/time i already know that Energy = Quantity so based on this, i can solve for Q = mass(ice)...
33. ### Kinematics physics homework help -- 2 canoes crossing a river

Homework Statement Two canoeists, A and B, live on opposite shores of a 300.0 m wide river that flows east at 0.80 m/s. A lives on the north shore and B lives on the south shore. They both set out to visit a mutual friend X who lives on the north shore at a point 200.0 m upstream from A and...
34. ### Basic Forces Question from 9th grader - Hard to put in words

Homework Statement I have here a problem asking me to find the tension force on the lower end of a rod with mass of 0.6 kg. The rod connects two blocks, the first / upper one has a mass of 5.0 kg while other/lower one has a mass of 4.0 kg. There is an upward force of 150 N applied on the whole...
35. ### Newtonian Mechanics/Forces Question

These buckets are being suspended. The cords have no mass and each bucket is 3.5 kg. a.) Find the tension in the upper cord (T1) and the lower cord (T2) b.) If the apparatus is pulled upwards from the top of the upper cord, what are the new tensions of each cord? I understand the...
36. ### Solving Physics Homework: Frequency Change

Homework Statement A cord vibrates with a frequency of 3.0 Hz when a mass of 0.60kg is hung up from it. What is its frequency if only 0.38kg hangs from it? Homework Equations f= 1/2pi sqrt k/m The Attempt at a Solution 3.0= 1/2pi sqrt ( k/0.6) k=213.18 N/m f= 1/2pi sqrt (213.18/ 0.38) f=...
37. ### Physics Homework Question on Electrostatic forces

Homework Statement Charge is distributed on the surface of a spherical balloon (an insulator). A point particle with charge q is inside. If polarization effects are negligible the electrical force on the particle q is greatest when: a. it is near the inside surface of the balloon b. it is at...
38. ### How to Calculate change in volume produced by a piston?

Homework Statement Hello all! I need a little bit of help with my physics homework! It asks me to calculate the change in volume produced by the piston, and it gives me the equation: ∆V= Ax∆dHomework EquationsThe Attempt at a Solution Now I know that A= 1x 10-^16m^2 And ∆d=1700nm My only...
39. ### Resolving forces in equilibrium on inclined plane

Homework Statement Solve for the forces P and N acting on an object in equilibrium on an inclined plane. Weight=10N, angle is 30 degrees http://blob:https%3A//www.physicsforums.com/d431a152-5681-411b-ba57-809320539165 Homework Equations Trigonometry, i.e. sin, cos, tan rules. The 'Z' rule...
40. ### Speed of Train B: Solving Physics Homework

Homework Statement Two trains run in opposite directions on parallel tracks. Train A is 30 meters long and runs east to west at 60 mph. Train B is 45 meters long and runs west to east. It takes 0.5 seconds for the trains to pass each other. How fast is train B travelling? What is the velocity...
41. ### Could Someone Look Over My Work? (particle accelerator design problem)

Homework Statement You want to construct a simple particle accelerator and hit on the following design: you will take two oppositely charged plates with small holes drilled into them and set them up parallel to each other. You will create a vacuum between the two plates and fire a beam of...
42. ### Applying Relative Motion to One Dimensional Motion Equations

<<Moderator note: LaTeX corrected>> Problem: > Two cars A and B move with velocity ##60 kmh^{-1}## and ##70 kmh^{-1}##. After a certain time, the two cars are 2.5 km apart. At that time, car B starts decelerating at the rate 20 kmh-2. How long does Car A take to catch up with Car B? I tried to...
43. ### [ansys] simulation of permanent magnet in 3D

Homework Statement The problem is to model a permanent magnet with a torus core .I just wanted to know how to attach attribute of magnet to a volume in ansys 15.0. I solved the problem in 2D but in 3D the results are not satisfactory and I'm not able to point out the mistake by me. the...
44. ### Period of Limit Cycle: Find B for Hopf Bifurcation

Homework Statement I'm given this system: \dot x = Ax^2 y + 1 - (B+1)x \dot y = Bx - Ax^2 y (a) Find the value of B when hopf bifurcation occurs. (b) Estimate the period of the limit cycle in terms of ##A## and ##B##.Homework EquationsThe Attempt at a Solution I have found fixed point to be...
45. ### How Should Spinors Be Applied in Physics Homework Involving Fermions?

Homework Statement Homework EquationsThe Attempt at a Solution I've started from writing out the amplitude. Here I know that fermion has definite helicity so I can't sum over spins but I should input explicit forms of spinors. Am I correct? How to do this? I would be grateful for helping me...
46. ### Torque Required to bring a drum to rest

Homework Statement I have a problem involving a goods lift with a cage m1 = 1500kg which is raised at V = 4m/s via a winding drum with a radius of 0.6m with the help of a counter weight of m = 900kg. i am asked to find the braking torque required to bring it to rest in 1 1/3 seconds. Also i am...
47. ### Uniform Circular Motion question

1. The problem The answer is A. Homework Equations x = Acoswt y = Asinwt The Attempt at a Solution C is not correct because the x & y positions are in terms of sin & cos, so the acceleration can't be constant. D is not correct because x & y are oscillating in value. E is not correct because...
48. ### How Does Planet X's Gravity Affect Rocket Escape Velocity?

1. Problem A rocket has landed on Planet X, which has half the radius of Earth. An astronaut onboard the rocket weighs twice as much on Planet X as on Earth. If the escape velocity for the rocket taking off from Earth is v , then its escape velocity on Planet X is a) 2 v b) (√2)v c) v d) v/2 e)...
49. ### How to Obtain a Magnification of -2 from a Convex Lens?

Homework Statement You wish to obtain a magnification of -2 from a convex lens of focal length f. The only possible solution is to: A) place a virtual object at a distance 2f/3 from the lens. B) place a virtual object at a distance 5f/3 from the lens. C) place a real object at a distance...
50. ### Help Solve Physics Homework: Computer Base Unit of Mass

Hi! Another Physics homework question that needs solving immediately! Thank you in advance. A computer base unit of mass 7.5 kg is dragged along a smooth desk. If the normal contact force is 23 N and the tension in the arm of the person dragging it acts at 23° to the horizontal, then what is...