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

    How to Derive Velocity from Newton's Second Law?

    Homework Statement Hi In a book they state \frac{dv}{dt} = a \quad \Rightarrow \quad v(z) = \sqrt{2a(z-z_{max})} I am trying to reproduce this. Here is what I have so far: dv/dt = (dv/dz)(dz/dt) = v(dv/dz) = a Since a is constant (I assume?), I get \int vdv = \int adz \quad...
  2. S

    Newtons 2nd law problem - how to interpret the break force

    Homework Statement A car travels on a horizontal street, straightforward. In some moment of time (t = 0), having a velocity of 20 m/s, the break is hit. It is required to find the time and traveled distance before the car is still standing. The friction coefficient between the wheels and the...
  3. N

    Newtons Law of Cooling - Determine rate of cooling

    An engine switched off and left to cool naturally will obey Newtons law of cooling. A particular engine is switched off at 105°C when the ambient temperature is 0°C. Its temperature falls according to the equation T=105e-0.025t °C. Where t=time in minutes. c) use calculus to determine the...
  4. S

    MATLAB Water Delivery System with Newtons Method

    1.We are asked to: i - Plot Wdot(pump) vs Q where v varies from 1 m/s to 50 m/s in increments of 1 m/s ii - plot P vs Q iii - write a function that uses Newtons method with a numerical derivative to calculate the friction factor -- function f = frict (e_over_d,Re) equations are below...
  5. S

    Is Every Example Listed an Illustration of Newton's First Law?

    Homework Statement Which situations below are examples of Newton's First Law? a) Your herd jerking back when car accelerates rapidly. b) Hitting shoe on wall to knock off snow. c) An apple hanging motionless on a tree. d) All of the above I know Newton's first law states that...
  6. J

    Comp Sci C++ programming, Newtons Method.

    Having a lot of trouble the my C++ course, loops especially. This is the assignment giving me trouble The function you are to implement finds a root of the given function eff(x) using Newton's method. The given version of eff(x) implements f(x) = x2e-x-2 (where e is the base of the natual...
  7. M

    Analyzing Forces on a Moving System: Newton's Second Law in Action

    Homework Statement I attached the photo of the question that has everything. Homework Equations F=ma The Attempt at a Solution So I found the total mass of the system 50+35 = 85. Since we are given the force in the x-direction I used \frac{70}{85} = a = .8235 . The weight of...
  8. P

    Derivation of Newtons equation of motion

    Homework Statement Hi there, I have been trying to use the Kalman filter to predict the location of some missing data with an 4D volume. I have coded it and got it to work but only because of the substational amount of literature which is availlable on the subject. What I am really confused...
  9. F

    Is Our Understanding of Gravity and Quantum Mechanics Incomplete?

    Seems like our general idea on the quantum level stops at predicting with great accuracy. The why, and hows seem to still evade us. Is my ideas accurate?
  10. johann1301

    Newtons first law should not be termed an expression of inertia

    Newtons first law should not be termed an expression of inertia LAW I. EVERY BODY PERSEVERES IN ITS STATE OF REST, OR OF UNIFORM MOTION IN A RIGHT LINE, UNLESS IT IS COMPELLED TO CHANGE THAT STATE BY FORCES IMPRESSED THERON. - «Isaac Newton`s Principa» In case inertia could be removed from a...
  11. D

    Is Newtons law of cooling related to the zeroth law of thermodynamics?

    Being that both laws explain some kind of heat transfer I was wondering if they are in any way related.
  12. S

    Modified Newtons cradle and the Conservation of Momentum

    Homework Statement 2 balls hang from a modified Newtons Cradle, on of mass 80g, the other of mass 200g. Assuming gravity is 9.81ms^-2 ball A is pulled out so it reaches a height of 10cm then released. After impact ball 2 moves at a speed of 0.80ms^-1... calculate the velocity of sphere A...
  13. A

    Moment of force and Newtons 2nd law

    By the end of the day, I must admit that the rotational analog of Newtons 2nd law: Τ = I*α contradicts my intuition. Suppose that you take a part of a body in the radius r from the rotational axis and exert a force on that. It will then get a linear acceleration. We can then find the angular...
  14. C

    Newtons third law and collision of bodies

    Hi friendz I m new to this forum I have a problem in a question which is as follows- If a body of mass m collides with a body of mass 2m it changes its direction of motion buy when it collides with a body of same mass m it stops and when it collides with a body of mass m/2 it does not change...
  15. M

    Why is a Non-Zero Root Used in Newton's Method for Sin(x) = x^2?

    Question: Use Newtons method to approximate the indicated root of the equation correct to six decimal places. The positive root of sin(x) = x^2 The answer is ...0.876726 Why did they pick this when the obvious root is 0? Sin(0) = (0)^2 = 0
  16. A

    Coloumbs law and Newtons third law

    Coloumbs law states that the force exerted by two charged particles on each other is given by f = kq1q2/d^2 Now say two charged particles (charge type irrelevant in question) x and y are d metres from each other then y exerts a force f on x. But since x is also exerting f on y then won't it...
  17. E

    How Do Aerodynamics Affect an Airplane's Lift and Drag Forces?

    1. an aeroplane of mass 300 tonnes during ascent travels at a constant velocity of 100 m/s. its angle of ascent is 10° to the horizontal. the trust produced by engines is 9000kN. Determine i)the lift force acting on the wings ii) the resistance to motion i were trying to use f=ma, but the...
  18. G

    Forces using Newtons Second law

    Homework Statement A 1300 kg car in neutral at the top of a 17° inclined 10 m long driveway slips its parking brake and rolls downward. At what speed will it hit the garage door at the bottom of the incline? Neglect all retarding forces. Homework Equations (sin17) (cos17)...
  19. G

    Forces using Newtons Second law

    Homework Statement A bullet fired into wet clay will decelerate fairly uniformly. If a 10 g bullet hits a block of clay at 235 m/s and comes to rest in 17 cm, what average force does it exert on the block? [Hint: From the fact that the bullet goes from vi to 0 in a distance s, you can find aav...
  20. E

    Calculating Necessary Newtons for Turning a 1m Wheel with 1kg Mass and 1cm Width

    How much Newtons is needed to turn a wheel with radius 1 meter and mass of one kilogram and width of 1cm, exerting force on the outer circumference of the wheel and assuming no friction occurs?
  21. E

    Question on banked curve, Application of Newtons Laws

    Homework Statement A turn in the road with a radius of 30m is banked at an angle of 40 degrees. If \mu=.75, what is the minimum and max speed a 1200 kg car can travel without sliding off the turn. Homework Equations F=ma, Mv^2/R, Fw = mg The Attempt at a Solution Alright, so...
  22. A

    Thermo: Newtons law of cooling for radiation

    Homework Statement A cube of copper of mass 4 kg and initial temperature of 110 oC is set to radiatively cool in an environment of 100 oC. (Note: copper has an emissivity of about 0.05. Also, neglect conduction and convection as cooling agents in this problem.) The surface area of the...
  23. 1

    Newtons Method and Finding the 5th root

    Homework Statement Find the 5th root of 36 accurate to four decimal places Homework Equations xn+1 = xn - f(xn)/f'(xn) The Attempt at a Solution First I attempted to write the fifth root of 36 in exponential form as show below: Let the 5th root of 36 = x Let f(x) =...
  24. T

    Calculating Force of Bird Impact Using Newton's 2nd Law

    This morning while riding my motorcycle, a black bird smashed into my helmet. Considering a black bird weighs approx. 80-120 gram (according to google), I was surprised by the force of the impact. Anyways, now I'm wondering if anyone could calculate with what force the bird hit the helmet...
  25. O

    Calculate Coefficient of Friction for 41N Bookcase on Ground

    Homework Statement what is the coefficient of friction between a 41N bookcase and the groud, when the bookcase accelerates at .25m/s2? Homework Equations F=ma Forcefriction=μ*force normal The Attempt at a Solution a=.25 m=41 μ=? I have absolutly no idea what i am doing
  26. S

    What is the acceleration of the minimum mass needed to prevent slipping?

    Figure shows a block of mass resting on a slope. The block has coefficients of friction and with the surface. It is connected via a massless string over a massless, frictionless pulley to a hanging block of mass 2.0 kg. i got this first one: What is the minimum mass that will stick and not...
  27. P

    Newtons of an exploding Supernova

    Is it possible to calculate the force in Newtons for a Supernova? Have any such calculations ever been possible or done by the scientific community? I can imagine the number would be in the trillions of trillions but I am simply interested.
  28. T

    Newtons Laws - Coefficient of Friction problem

    Homework Statement The Attempt at a Solution I found the acceleration using kinematics equations. I don't know how to find the coefficient of friction though. I need help answering pard b c and d If you could give me the equations and explain. Just knowing how to do this one...
  29. T

    Need help with Newtons laws. finding normal force.

    Homework Statement It includes a diagram so i just took a screenshot of the question. I don't undertand how to do this problem Thanks
  30. L

    Newtons Law Problem involving kinematic equation

    Homework Statement A duck has a mass of 3.0 kg. As the duck paddles, a force of 0.06 N acts on it in a direction due east. In addition, the current of the water exerts a force of 0.13 N in a direction of 60° south of east. When these forces begin to act, the velocity of the duck is 0.12 m/s...
  31. K

    Newtons third law and elevators

    If two objects are stacked in an accelerating elevator what is the force equal and opposite to the normal force on the top object? I was thinking that it has to be either the force of gravity or contact force between the two objects could it be anything else?
  32. A

    Does a rocket/spacecraft moving in space violate Newtons laws?

    How does a spacecraft move in space where there is vacuum and nothing to provide normal reaction for the motion?
  33. A

    Calculating Friction Forces in a System of Blocks Connected by Cords

    Homework Statement Homework Statement the blocks shown in the figure are connected by flexible, inextensible cords passing over frictionless pulleys. at A, the coefficient fiction is 0.30 while at B, it is 0.40. compute the magnitude and direction of the friction forces and each block...
  34. C

    Problem using Newtons second law

    Once her chute opens, a sky-diver of mass m is acted upon by a downward force Fg due to gravity, and an upward force Fr due to air resistance. If Fg = mg, where g is gravitational acceleration, and Fr is proportional to velocity v, use Newton’s Second Law of Motion to write acceleration a as a...
  35. A

    Newtons Three Laws and Force Question

    Homework Statement A rocket that weighed 98.1 N when put together on Earth is attached to a 1.00 x 10^3-kg signal relay in intergalactic space. The rocket develops a constant thrust (i.e., it pushes with a force) of 10.0 kN. Compute the resulting acceleration. Homework Equations a=F/m...
  36. V

    Conservation of momnetum or Newtons second law?

    conservation of momnetum or Newtons second law? Homework Statement An acrobat of mass 'm' clings to a rope ladder hanging below a balloon of mass 'M'. the balloon stationary with respect to ground (a) If the acrobat begins to climb the ladder at a speed 'v' (with respect to the ladder), in...
  37. I

    Newtons third law regarding spacecraft engines

    Hello PF members, I was wondering whether Newtons third law was exclusive to spacecraft thrust; space being empty and without enough particles for a force to push against. That in order to produce thrust in space, you would need to carry the fuel that you plan to eject with you...
  38. T

    Violation of Newtons Third law

    I've heard many times that Newtons third law is violated in electromagnetism, but I never knew why. I found this link...
  39. Vorde

    Use of Calculus in Newtons Laws

    Why do I see Newtons 3 laws (mostly 2 and 3) given using differentials (F=dp/dt etc...) when it is far simpler to use the basic form F=ma (and the same for the 3rd law), is there an advantage to the more complicated form?
  40. V

    How Does Newton's Second Law Apply to a Bird Sitting on a Wire?

    Homework Statement fill in the blanks. when a bird of weight W sits on a stretched wire, The tension in the wire is__________ Homework Equations Force(external)=mass*aceeleration The Attempt at a Solution tension should approach to infinity...
  41. A

    Problem with Newtons Laws of Motion

    Homework Statement There are 2 blocks, one of mass m kept over other of mass 2m. Pls. refer to the diagram. The question is : the minimum value of u (coefficient of friction) between the 2 blocks for no slipping is : (a) F/mg (b) F/3mg (c) 2F/3mg (d) 4F/3mg My answer is coming as (b) but...
  42. V

    Newtons work and double derivative.

    I have read kinematics and laws of motion(1st,second and third). In these two chapters one thing i found that firstly distance is taken as first assumption.then it's derivative as velocity OK. then it's(velocity) derivative is taken as acceleration OK. Then it's derivative(acceleration) is...
  43. N

    Newtons second law about momemtum

    Homework Statement a mass of 10kg, initially at rest, is acted on by a force of 10N for 10 s. What is the final velocity of the mass? Homework Equations i think this equation should help: F= change in momentum/ time The Attempt at a Solution hey everyone i am out of school so...
  44. A

    Position of a body moving by Newtons Univ. Law. of Grav., at a point in time

    Hi all, I am trying to code a simulation that pins two bodies against each other and animates their motion. I am using Sun and Earth as example, with preset positions and velocities, and Newtons Law of Universal Gravitation formula. It all works quite alright, up until I have decided to link...
  45. S

    New to physics and with Newtons laws

    What force is required to accelerate a 10g bullet from rest to 200m.-1 in a rifle barrel 50cm long i don't need the answer just how to work it out
  46. K

    Solving for a Train Without Knowing Mass

    A train is traveling up a 3.73 degree incline at 3.25 m/s when the last car breaks free and begins to coast without friction. A) How long does it take for the last car to come to rest momentarily? B) How far did the last car travel before coming to rest? Newtons Second Law I know...
  47. alyafey22

    Newtons vs. Pounds: Why Do We Use Them?

    it was really tough to me to understand the relationship between the Newtons and Pounds, not in mathematical term that lb=4.45 N , but I always find problems to understand why do people use it >>> and why Pound does equal approximately half of Newton << I mean what is the first to be found ...
  48. Femme_physics

    Mass and weight, kg and Newtons

    If I know an object has a mass of 5 kg, and I want to find its weight on earth, I multiply it by 9.81 - right? That equals 49.05 kg. Now, if I want to convert it to Newtons, I multiply it by additional 9.81 So it would equal 481.18 [N]? Is that right?
  49. M

    What is the Tension in a Pulley System with Two Connected Masses?

    Homework Statement [PLAIN]http://img703.imageshack.us/img703/3580/12p71.jpg m1 = 1,378 g. It is free to move along a horizontal, frictionless surface. This block is connected to a second block with mass of m2 = 872 g by a massless string that extends around a massless, frictionless pulley...
  50. S

    Need to demonstrate 44 Newtons of force

    I hope someone can help me. I am a medical doctor and need to have a standardized way to demonstrate the force needed to press on the front of the cricoid ring of the larynx (neck) in order to occlude the esophagus (Sellick's maneuver) with the patient lying supine... so the thumb and...
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