Newtons Definition and 502 Threads

The newton (symbol: N) is the International System of Units (SI) derived unit of force. It is named after Isaac Newton in recognition of his work on classical mechanics, specifically Newton's second law of motion.
A newton is defined as the force which gives a mass of 1 kilogram an acceleration of 1 metre per second, per second, 1 kg⋅m/s2.

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  1. N

    What is 400 Newtons and How Does it Relate to Everyday Life?

    I'm a middle school history teacher and I have to explain to a group of parents what 400 Newtons is. It's a long story... I've googled Newtons and understand that they're a measurement of force. It would be great if someone could give me some real world examples of what can produce a force...
  2. T

    Newtons law of motion questions

    Homework Statement Tell me what is wrong with this question- A donkey which has heard of Newtons third law but not understood it very well refuses to pull a cart attached to it because it argues that: ' If i pull on the cart with a certain force, Newton's third law would imply an equal but...
  3. G

    Newtons 2nd Law of motion Practical Questions

    So i have a few questions in relation to a practical completed in grade 11 Physics The basic experiment about the 2nd law, in which a hanging weight is used to accelerate a cart the practical also had a 2nd part in which weights were added to the small cart to decrease the acceleration while...
  4. J

    Help with Newtons 2nd applied to Rocketry

    This is a direct quote from nasa.gov. I understand everything up until the last equation. Can it not be written like F = mdot(v2-v1) ? Also, this equation F = d(mv)/dt is the same as this F = (m dot * V)e - (m dot * V)0 ? Or no? I understand Mass x Velocity is momentum and they want the...
  5. E

    Showing forces between 2 current loops are in accord with Newtons 3rd law

    Homework Statement show that the forces between two current loops obey Newtons 3rd law. Homework Equations \textbf{F}_{12}=\frac{\mu I_{1}I_{2}}{4 \pi s^{2}} d\textbf{r}_{1}\times(d\textbf{r}_{2}\times \textbf{s}) s is the distance between the elements of current The Attempt at a Solution...
  6. T

    Angular momentum and Newtons' law relation

    Hi I'm obsessed with this angular momentum conservation thing.From second law we can understand the linear momentum conservation easily, but in angular momentum i can't understand the logic.There comes a cross R which is the position vector.I searched a lot about this and couldn't find a...
  7. B

    Is it possible to hate Newtons Laws?

    Is it possible to hate Newtons Laws? Hi, I am taking a course in physics, and I have noticed that Newtons Laws, and Newtons Mechanics just bores me to death whenever I am reading about it or trying to do questions. On the other hand, we started to do some Energy and Work chapters, and the...
  8. M

    Newtons Law on Gravitational Force

    this is going to sound dumb, but here i go. through out my schooling i was preached " in a vaccum, a feather and a bowling ball would fall at the same rate". -thinking about the difference in theories with Aristotol, Galileo, and Newton, something didn't make sense to me. Talking about...
  9. V

    Could Gravitational Attraction Explain the Bond Between Man and Dog?

    Homework Statement Imagine taking your dog for a walk. You feel a real bond for man's best friend. Could this be due to gravitational attraction? Estimate the force of gravity between you and your dog. Homework Equations force~mass1 x mass2 divided by distance^2 The Attempt at a...
  10. J

    Rotation with Newtons second law and work energy

    Heres the problem http://img141.imageshack.us/img141/2820/49686394mt3.jpg Now I have to work it out using Newtons second law and Work energy... For Newtons second Law (F = ma)...would I be using I = mk^2 M = I\alpha than setting up F = ma...? and for work energy I am...
  11. V

    Inclined Plane Newton's Law Problem

    Homework Statement Check out my attachment to get an idea what is happening. What we have is an inclined plane with 2 masses (m1 and m2) which are touching one another and the angle of the incline is 30 degrees. The coefficient of kinetic friction between m1 and the plane is 0.23 = mu_k1...
  12. B

    Time to Pass 30m - Joe's Car 4.33s

    Joe was driving on the highway a car ahead of him was driving far below the speed limit so he decided to pass. In the first second he gained(gained means to get nearer to something you are chasing) 5m on the car and as he accelerated he gained 1.5 times as much distance in each second as he had...
  13. M

    Engineering Problem, Newtons Law based, Any help would be great

    Hi guys. This is my first post. I am currently on an engineering apprenticeship and its mostly practical but i have been given a Newtons law question which i am finding very hard. I have attempted it but still come up stuck. I have attached the question with the drawing. I have...
  14. H

    Help needed - Newtons first law - particles in equilibrium

    For some odd reason, I'm having no problems with the rest of the exercises, though this one is really annoying as i just can't seem to get it right. Here's a picture of the exercise h t t p://img2.freeimagehosting.net/image.php?4bc2e12442.jpg...
  15. B

    Acceleration and Newtons gravitation

    I was thinking about Newtons law and come across something interesting. F=ma=GMm/r^2 therefore a=GM/r^2. This is the acceleration of the satellite towards the larger mass. But this acceleration is only accurate assuming that the larger mass is stationary. But f=Ma=GMm/r^2, so there is an...
  16. G

    How Does the Sun's Gravitational Pull on the Moon Compare to Earth's?

    Homework Statement What is the ratio of the gravitationalpull of the sun on the moon to that of the Earth on the moon?(Assume the distance of the moon from the suncan be approximated by the distance of the Earth from the sun.) Homework Equations F_{g} =...
  17. M

    How do I find the work and power if I have a mass in Newtons?

    Im trying to find my work when climbing up stairs. If I convert my weight into Newtons, do I still need to multiply it by 9.8? Since i weigh 135, I multiplied that by 4.5 to get my weight in Newtons. I then multiplied that by 9.8, after that I multiplied that by 3.0 m ( the distance of the...
  18. X

    Newtons law, interacting objects question?

    Newtons law, interacting objects question?? A block of mass 5.00 Kg sits on top of a second block of mass 15.0 Kg, which in turn sits on a horizontal table. The coefficients of friction between the two blocks are : μs = 0.300 and μk = 0.100. The coefficients of friction between the lower...
  19. O

    FORCES applications of Newtons law

    can someone please help to reason out this. because i am confused...is the question about static friction..please help On a truck which is moving straightforward on an horizontal road there is a big cube of concrete of mass m. The mass of the truck is M. The truck brakes suddenly with an...
  20. S

    Why are N and mg equal in magnitude?

    Hey guys, was just wondering if you could explain the answer to this question. So basically we have a picture of a book resting on a table. On this book there is the weight force downwards and the reaction force upwards, both acting on the center of mass. The question: A class of students is...
  21. T

    Slope Represents Newton's Second Law

    [SOLVED] Newtons Second Law Homework Statement On a force/mass vs acceleration graph where force/mass is horizontal, what does the slope represent? Homework Equations The Attempt at a Solution My calclations: ex. (2m/s^2 - 1m/s^2)/(3 N/kg - 1N/kg) =.5 (m/s^2)/(N/kg)...
  22. W

    Newtons Law Problem: objects and pulleys

    Homework Statement three blocks attatched by cords that loop over frictionless pulleys. Block B lies on frictionless table, block a hangs off the left side of the table, while block c hangs off the right side. mass a= 6kg mass b= 8kg and mass c= 10kg. When the blocks are released, what is the...
  23. I

    How Do Newton's Laws Apply to a Lemon Half on a Frictionless Surface?

    [b]1. A figure shows an overhead view of a lemon half and two of the three horizontal forces that act on it as it is on a frictionless table. Force F1 has a magnitude of 4.70 N (in the negative x and positive y direction) and is at θ 1 = 29°. Force F2 has a magnitude of 7.00 N (in the positive x...
  24. G

    Converting Newton's Law of Cooling from Heat Loss to Temperature Decay

    Homework Statement The equation dQ/dt = k ( T - Troom) is Newtons law of cooling. dQ/dT being the rate of heat loss. I want to convert this equation to dT/dt, the rate of temperature decay. How do i go about doing this? Homework Equations The Attempt at a Solution Is Q...
  25. D

    Proportional Masses Newtons Laws

    A red box and a blue box sit on a horizontal, frictionless surface. When horizontal force F is applied to the red box, it accelerates 4.88 m/s2. a) If F is applied to the blue box, it accelerates at 1.32 m/s2. What is the ratio of the masses of the boxes (mass of the red box/mass of the blue...
  26. D

    Frictional forces acting on log Application of Newtons Laws

    A rope is tied to a 97.8 kg log. When you pull on the rope with a horizontal force of magnitude 706 N, the log moves at constant speed. a) Find the magnitude of the resistive (frictional) force acting on the log. You may assume the frictional forces acting on the log is constant. N b)...
  27. D

    Physics Homework Problem Newtons Laws of Motion

    I have this problem on a web assignment due on the 20th of this month. A few of the problems have completely blown my mind including the following: A force F0 causes an acceleration of 18 m/s2 when it acts on an object of mass m sliding on a frictionless surface. Find the magnitude of the...
  28. H

    Newtons Laws - Boxes connected with a cord

    Homework Statement A block A (mass 2.25k) rests on a tabletop. It is connected by a horizontal cord passomg over a light, frictionless pulley to a hanging block B (mass 1.3kg). The coeffisient of kinetic friction between block A and the tabletop is 0.45. After the block is released from the...
  29. J

    Newtons Law of Gravity Legendre Polynomial & Harmonic functions

    I'm reading section 17 of Mathematical Physics by Donald H. Menzel on Harmonic functions. They start with Newtons law of gravitation (although the following method can be aplied to any potential field with a 1/r dependence.) see...
  30. J

    Solving for Normal Force and Tension in a Tensioned Rope System

    Homework Statement You are dragging a stack of shoeboxes along the floor by a rope (an odd situation I must say). If the total mass of the shoeboxes is 18kg and the rope is pulled at an angle of 45 degrees with no acceleration i) what is N (normal force)? and ii) What is the tension of...
  31. S

    Why Doesn't a Windshield Shatter When a Fly Hits It at High Speed?

    Hey guys, I was just wondering if you could help me with a question that has been bugging me for a while now. I've thought of many possibilities to the answer yet i still can't find the right one. The question is that, when a fly strikes the windshield of a truck moving at let's say 60km/h, why...
  32. B

    How Do Forces Affect Acceleration on a Frictionless Surface?

    a 20 kg box is on frictionless surface acted on by two horizontal surfaces. when in same direction, it pulls 11 m/s but in opposite directions, it pulls only 1 m/s. determine magnitude of each force. answer: 120 N , 100 N okay...i need help with this. i am using Newtons law: force=mass x...
  33. I

    Solving Newtons 2nd Law Homework: Velocity of Rocket on Ground

    Homework Statement Ok this is kind of long. This is the 4th question on my homework assignment and I need to give background on the first 3 to make sure I got those correct. 1. I am sure on this since it was simply finding the weight of a rocket ship that has an intial mass of 3kg. Answer is...
  34. K

    What is the maximum acceleration a runner can achieve with 90% friction?

    Hey all, I am new to Physics. Recently changed majors from technical writing to physics for the amount of interest I have in the subject. I have been doing ok but I missed a couple of questions on my last homework and I feel that I should have had somebody check my general solved statements...
  35. B

    How Is Force Calculated for an Object Falling Under Gravity?

    hi, I am not really sure where this belongs, and being a complete noob at physics, i was just enquiring if someone could inform em of the formula to calculate the distance an object weighing 80kg would need to fall in order to be effected by 4,400 Newtons?
  36. F

    Hamiltons Principle proving Newtons laws?

    My teacher asked us too prove that Hamiltons principle proves that Newtons equations of motion hold for N particles. I'm not sure that i fully grasp the concept but this is my understanding so far: Using the lagrangian we can prove Newtons law for specific situations, however Hamiltons...
  37. N

    Understanding Newton's Third Law: Why Does a Rocket Go Up?

    I have spent a ton of time researching my question but i can't find the answer i know that for every action there is an equal and opposite reaction i know if you have a tire on the ground and when it starts spinning it pushes so that the concret will go the other way but the ground it to...
  38. O

    Proof of Newtons gravitational law?

    proof of Newtons gravitational law!? hi every one, i am new in this forum n here is my first question that really bothers me for a long time we always take for granted the formula given by Newton F=G*(M1*M2)/R^2 do u have any proof that is really satisfing.n i don't understand why Earth is on...
  39. D

    Why Do Objects Move Despite Equal and Opposite Reactions?

    It says that every reaction there is a opposite and equal reaction. Why do things still move if everything is opposite and equal?
  40. H

    Calculating Mass on a Frictionless Surface

    http://img75.imageshack.us/img75/9735/prob1ve7.jpg Frictionless surface, pulled along a horizontal line, string has no mass Calculate the mass m The answer says 17,1 kg, i don't know if it is correct, can sum1 please give a solution with the steps:smile:
  41. A

    Calculate the magnitude in Newtons of the normal force

    Homework Statement A plank, of length L = 3.7 m and mass M = 7.0 kg, rests on the ground and on a frictionless roller at the top of a wall of height h = 1.70 m (see the figure). The center of gravity of the plank is at its center. The plank remains in equilibrium for any value of θ >= 74° but...
  42. N

    So what is the force in Newtons?

    given mass= 100kg and it's a freely falling body. so what is the force in Newtons??
  43. R

    Convert .130 kg to Newtons: Is Gravity Relevant?

    If I have a small model car and use a spring scale to measure the force, my reading is .130 kg. How do convert that to Newtons? Is gravity relevant to this equation? I know that F = m x a the mass of the car is .387 kg is the accerleration the acceleration of the car or gravity?
  44. P

    Exploring the Speed of Electrons and Impulses in Newtons Cradle

    hey dudes i read in a book that when an electric current flow that the electrons move preety slow [maybe 1mm/s I'm not sure] now i also know electricity travels at the speed of light (ideally) so that an electron c*1s away will take 1s to start moving after i close the circuit so i was...
  45. S

    Confirm the differential equation for a falling rope using Newtons law

    Homework Statement A uniform chain of length L, measured in feet, is held vertically so that the lower end just touches the floor. The chain weighs 2lb/ft. The upper end that is held is released from rest at t = 0 and the chain falls straight down. Ignore air resistance, assume that the +...
  46. O

    What Determines the Collision Speed of Two Unequal Mass Asteroids?

    Homework Statement Two spherical asteroids have the same radius R. Asteroid 1 has mass M and asteroid 2 has mass 2.58·M. The two asteroids are released from rest with distance 12.35·R between their centers. What is the speed of second asteroid just before they collide? Give answer in units...
  47. E

    Calculating Acceleration and Tension in a Pulley System with Inclined Planes

    Please help me because my teacher has not explained how to do questions involving angles. Blocks X and Y of masses mx=5.12kg and my=3.22kg are connected by a fishing line passing over a frictionless pulley. Show that block X slides up the incline (35.7 degrees above the horizontal) with...
  48. T

    NWhat is the Apparent Weight of a Bicyclist on a Hump?

    A bicycle of bicyclist of combined masss 62 kg go over a hump of radius 6m at a speed of 5m/s. what is their combined appararent weight at the top of the hump? is it just... Fc = MAc Fc =M(V^2/r) Fc = 62(25/6) Fc = 290N
  49. T

    How Do Newton's Laws Explain Motion in Everyday Scenarios?

    (1) What is the magnitude of the net force on a skydiver in N when an 810 N gravitational force and a 750N force of air resistance act on him? Fn = 810 Fg = 750 810 - 750 = Fm 60N (2) A 1200 kg car is moving in a staright line at a constant speed of 15m/s when the brakes are...
  50. S

    Calculating Forces on Inclined Surfaces

    Homework Statement 1) The coefficient of kinetic friction for a 22-kg bobsled on a track is 0.10. What force is required to push it down at a 6.0 degree incline and achieve a speed of 60 km/h at the end of 75 m? 2) A box is given a push so that it slides across the floor. How far will it go...
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