Newton's second law Definition and 264 Threads

In classical mechanics, Newton's laws of motion are three laws that describe the relationship between the motion of an object and the forces acting on it. The first law states that an object either remains at rest or continues to move at a constant velocity, unless it is acted upon by an external force. The second law states that the rate of change of momentum of an object is directly proportional to the force applied, or, for an object with constant mass, that the net force on an object is equal to the mass of that object multiplied by the acceleration. The third law states that when one object exerts a force on a second object, that second object exerts a force that is equal in magnitude and opposite in direction on the first object.
The three laws of motion were first compiled by Isaac Newton in his Philosophiæ Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy), first published in 1687. Newton used them to explain and investigate the motion of many physical objects and systems, which laid the foundation for Newtonian mechanics.

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  1. D

    Newton's Second Law & Moment of Inertia Derivation?

    Homework Statement We did something very similar to this in lab http://webenhanced.lbcc.edu/physte/phys2ate/2A%20LAB%20HANDOUTS/Moment%20of%20Inertia.pdf Use Newton's Second to derive the expression for the experimentally determined moment of inertiaHomework Equations Newton's Second Law is...
  2. Q

    Help With Net Force Formula and Newton's Second Law

    Homework Statement 1. Compare the mass of the system to the slope. Does your data support Newton's Second Law? 2. Using the words "directly" or "indirectly" briefly explain how force, mass, and acceleration are related to each other, making specific references to the parts of the...
  3. P

    Newton's Second Law for a System of Particles

    Homework Statement A shell is shot with an initial velocity 0 of 29 m/s, at an angle of θ0 = 56° with the horizontal. At the top of the trajectory, the shell explodes into two fragments of equal mass. One fragment, whose speed immediately after the explosion is zero, falls vertically. How far...
  4. T

    Problems with Newton's Second Law

    Homework Statement Given a car being pushed by a constant force: a. How will the acceleration change in relation to the mass of the car? --> Done, it'll decrease b. How will a graph of acceleration in the y-axis and and (1/m) being the x-axis will look like? What will the slope of the...
  5. M

    The Vector nature of Newton's Second Law

    Homework Statement A wagon carries a child. Together mass is 28.5kg. You pull on the handle of the wagon at an angle of 40degrees from the horizontal. The wagon travels over a level horizontal sidewalk. A force of friction of 12.0N acts on the wagon. a) What is the net force acting on the...
  6. M

    Newton's Second Law: Calculating Net Force on a Wagon with a Child (28.5kg)

    A wagon carries a child. Together mass is 28.5kg. You pull on the handle of the wagon at an angle of 40degrees from the horizontal. The wagon travels over a level horizontal sidewalk. A force of friction of 12.0N acts on the wagon. a) What is the net force acting on the wagon? Note...
  7. T

    The Vector Nature of Newton's Second Law

    Homework Statement A crate of mass 50.0 kg is pulled across a level concrete floor by a force of 300.0 N acting 30.0 degrees above the horizontal. The crate moves at a constant velocity of 0.962 m/s. What is the force of friction acting on the crate? Homework Equations SINE, COSINE...
  8. C

    Newton's Second Law and Inertial Frames Of Refence

    I have a question about Newton's Second Law and Inertial Frames of Refrence. It is canon that Newton's Second Law is only applicable in an inertial frame of refrence. Newton's Second Law is the net force acting on a body is equal to the time rate of change of the body's linear momentum...
  9. A

    Newton's second law net force = mass

    Homework Statement True or false: "Given that the same force acts on particle A and B, If object B covers the same distance in less time than particle A, object B is less massive than object A" Homework Equations net force = mass(acceleration) The Attempt at a Solution I believe...
  10. E

    Question about Newton's second law

    A 4.0 kg block is put on top of a 6.0 kg block. In order to cause the top block to slip on the bottom one when the latter is held fixed, a horizontal force of 12N must be applied to the top block to overcome the maximum static friction. The coefficient of kinetic friction for all contact...
  11. S

    How Do You Calculate Force and Acceleration on an Inclined Plane?

    Homework Statement The 60 kg block starting at rest is pushed 7.8 m up a ramp at an angle θ = 26.5° to the horizontal in 15 s. If the coeficient of kinetic friction is 0.17: What is the acceleration of block? What is the force used to push the block up the ramp? Homework Equations Fnet...
  12. U

    Question related to Newton's second law

    Homework Statement Given data: - The weight of (A) is 3.6 N. - The weight of (B) is 5.4 N. - The kinetic friction coefficient between all surfaces is 0.25 http://img369.imageshack.us/img369/2999/figurehg3.png The problem statement: Find the required force for dragging (B) with a...
  13. S

    How Does Elevator Acceleration Affect Scale Readings?

    Homework Statement A 60.0 kg person stands on a scale in an elevator. (solve in Newtons) What does it read when the elevator is accelerating upward at 3.5 m/s2? What does it read when the elevator is accelerating downward at 3.5 m/s2? Homework Equations Fnet = ma The Attempt at...
  14. P

    Need help on question Newton's second law

    [b]1.Bsed on Newton's 2nd law,predict what will happen to the spaceshutter's acceleration after a lift as it burns its fuel Homework Equations F=ma The Attempt at a Solution since fuel is being burnt, thus mass of space shutter is decreasing as fuel is being burnt. force is...
  15. J

    Newton's second law and a locomotive

    Homework Statement A 50,000 kg locomotive is traveling at 60.0 when its engine and brakes both fail. How far will the locomotive roll before it comes to a stop? I'm completely lost and i don't know how to get started on this question
  16. N

    Question on Newton's Second Law of Motion

    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...
  17. N

    Question on Newton's Second Law of Motion

    Homework Statement Here's the question: An arrow, starting from rest, leaves the bow with a speed of 25.0 m/s. If the average force exerted by the bow were doubled, all else remaining the same, with what speed would the arrow leave the bow? Homework Equations F = ma The Attempt...
  18. F

    Newton's Second Law for Rotation

    Homework Statement A pulley, with a rotational inertia of 1.0 x 10^-3 kg*m^2 about its axle and a radius of 10 cm, is acted on tangentially at its rim. the force magnitude varies in time as F=0.50t + 0.30t^2, with F in Newtons and t in seconds. The pulley is initially at rest . At t=3.0 s...
  19. A

    HW: Newton's Second Law and Angles

    [SOLVED] HW: Newton's Second Law and Angles Homework Statement The system shown in the figure can be used to measure the acceleration of the system. An observer riding on the platform measures the angle (theta) that the thread supporting the light all makes with the vertical. There is no...
  20. B

    Using Newton's Second Law for a System of Particles

    The Problem: A 4 kg dog stands on a 16 kg flatboat at distance 12 m from the shore. The dog walks 5 m along the boat toward the shore and then stops. Assuming no friction between the boat and the water, find how far the dog is then from the shore. The dog's displacement is towards the shore...
  21. X

    Newton's Second Law of Motion acceleration problem

    An object (mass 10.0 kg) slides upward on a slippery vertical wall. A force F of 60 N acts at an angle of 60 degrees (the force is 60 degrees South of the x+ axis, it's shown in a picture) Determine the normal force exerted on the object by the wall. Next, determine the object's acceleration...
  22. F

    Comparing Acceleration and Force Graphs: How Do They Relate?

    Graphs Of Acceleration And Force Hi! We did this lab...on Newton's Second Law. we are trying to prove the formula F=ma... Now i drew this graph of acceleration vs time and force vs time...they look similar..how can i interpretate them? someone help! MY lab is due tomorrow!
  23. R

    Newton's second law and a weight and string

    Homework Statement suspended a heavy weight from a light string and attach a similar string below it. if you pull on the lower string with a steadily increasing force, the upper string will break; if you pull the lower string with a jerk, the lower string will break. please explain to me...
  24. K

    Newton's Second law problem; rail and cart model.

    Homework Statement A 800 g steel "cart" has a square steel rail running through the middle of it, touching the steel cart on all four sides of the rail. An elastic cord attached to the front of the cart and the "ceiling" of the apparatus creates a 45 degree angle from the horizontal axis in...
  25. R

    How the wave equation relates to Newton's Second Law of Motion

    Homework Statement Open Question 3.bmp Homework Equations The Attempt at a Solution Open Answer 3.bmp Any help with this would be greatly appreciated
  26. M

    Newton's Second Law of Rotation

    Homework Statement We have a rigid bar (length L) with an axis of rotation through the center of the bar. The bar is attached to a pulley with radius Rp at the axis of rotation. Two lead weights (mass M) can be screwed on the bar at equal distances R from the axis of the pulley. In each trial...
  27. J

    Newton's Second Law of Motion homework problem

    An applied force accelerates mass A at a rate of 6.0m/s^2. The same force applied to mass B accelerates the mass at a rate of 8.0m/s^2. If the same force were used to accelerate both masses together, what would be the resulting acceleration be?
  28. S

    Armadillo Problem (Newton's Second Law)

    Homework Statement For sport, a 12 kg armadillo runs onto a large pond of level, frictionless ice with an initial velocity of 5.0 m/s along the positive direction of an x-axis. Take its initial position on the ice as being the origin. It slips over the ice while being pushed by a wind with a...
  29. P

    Calculating Mass of Little Sister Using Newton's Second Law

    You are pulling your little sister on her sled acroos an icy(frictionless) surface. When you exert a constant horizontal force of 110 N, the sled has an acceleration of 2.5 m/s^2. If the sled has a mass of 7 kg, what is the mass of your little sister? Heres how I attempted it: F=110N A=2.5...
  30. J

    Newton's Second Law - Machine Problem

    A machine has an 760g steel shuttle that is pulled along a square steel rail by an elastic cord . The shuttle is released when the elastic cord has 16.0N tension at a 45º angle. What is the initial acceleration of the shuttle? Here is the only photo associated with this...
  31. S

    Newton's Second Law Particle Problem

    Homework Statement While two forces act on it, a particle is to move at the constant velocity v = (3 m/s)i - (4 m/s)j. One of the forces is F1 = (2N)i + (-6N)j. What is the other force? Homework Equations Fnet = ma The Attempt at a Solution Well, I'm really just wanting a...
  32. P

    How Is Average Force Calculated in Ball Bounce Dynamics?

    Homework Statement After falling from rest at a height of 29.8 m, a 0.596 kg ball rebounds upward, reaching a height of 23.9 m. If the contact between ball and ground lasted 1.68 ms, what average force was exerted on the ball? Homework Equations The Attempt at a Solution so I...
  33. S

    How Do You Calculate the Net Force on a Moving Object Using Newton's Second Law?

    Homework Statement A 3.00kg object is moving in a plane, with its x and y coordinates given by x=5(t^2)-1 and y = 3(t^3) + 2, where x and y are in meters and t is in seconds. Find the magnitude of the net force acting on this object at t=2.00s Homework Equations F = ma The Attempt...
  34. O

    Newton's second law integration

    I need to integrate \frac{mdv}{F(v)} = dt to show that t = m \int^{v}_ {vo} \frac{dv '}{F(v ')} Now, I now that velocity is the derivative of position, and the mass is constant, but how does one integrate F(v)? [Integrating is a weak spot for me] Thanks in advance!
  35. M

    Solving Newton's Second Law: 3 Blocks, 667 N Force

    Can somebody please give me hints as to how to approach this problem? Three blocks are in contact with each other on a frictionless horizontal surface. [order: 2.8kg, 6kg, 7.7kg] A 667 N horizontal force is applied to the block with mass of 2.8kg. What is the net force on the block with mass...
  36. S

    Newton's Second Law in NON-inertial frame of reference

    Homework Statement The steel ball is suspended from the accelerating frame by the two cords A and B. The angles (they are on the inside) are both 60 degrees. Determine the acceleration of the frame which will cause the tension in A to be twice that in B. The acceleration is going to the...
  37. A

    Newton's Second Law and car acceleration

    I'm having a hard time understanding this. If a car that has a constant acceleration hits me let's say at 10km/h then at 100km/h will it exert the same amount of force on me? F= ma mass and acceleration are constant. But this doesn't seem right, does it? Do you guys know any good website or...
  38. X

    Newton's second law with two objects

    My textbook is Essential University Physics by Richard Wolfson. I'm attending Illinois Central College, and my course is Engineering Physics 1: Mechanics. It's calculus based. Homework Statement From the Text: "A florist asks you to make a window display with two hanging pots as shown in...
  39. A

    Calculating Net Force on an Otter Using Newton's Second Law

    1. A 2.0 kg otter starts from rest at the top of a muddy incline 85 cm long and slides down to the bottom in 5.0 s. What net force acts on the otter along the incline. 2. Homework Equations - F=ma, maybe some more too. 3. The Attempt at a Solution I attempted this question for...
  40. S

    Newton's 2nd Law: Conditions & Application

    hmm...i was wondering is there any conditions for the use of Newton's second law?
  41. O

    Problem - Newton's second law applied to uniform circular motion

    Here is the problem I am working on: http://img45.imageshack.us/img45/5566/image0002bv6.jpg Here is my work: http://img177.imageshack.us/img177/7127/image0001zy6.jpg I cannot solve (2) for v since there are no real roots. When I set up the net forces in the x-direction in (1), should I...
  42. E

    Hw help with vector natur of Newton's second law of motion

    only two forces act on an object (mass = 3.00 kg). 40.0N east and 60.0N north of east at 45 degrees. Find the magnitude and the direction (relative to the x axis) of the acceleration of the object. I don't really know where to begin.
  43. R

    Force using Newton's second law

    A child slides down a slide with a 28 degrees incline and at the bottom her speed is preisely half what it would have been if the slide had been firctionless. Caluclate the coefficient of kinetic friction bewteen the slide and the child.
  44. M

    Pendulum mass and Newton's second law

    hello:) i have a question: if i changed the mass of the ball on the pendulum, i assume that Changing the mass of the ball would not change the period of the pendulum because gravity pulls objects towards Earth at the same speed regardless of their mass. however Newton's second law says that...
  45. M

    Newton's Second Law: Light & Heavy Objects, Same Force & Acceleration?

    I know that violating physics laws is impossible; this is just a question, so just answer it and don't say that can't happen. Anyways, if there is a light object and a heavy object, and forces of the same magnitude are exerted on the the objects, and despite the heavier mass, the heavier object...
  46. Gamma

    Newton's second law and the egg drop

    Hi, I have a question on Newton's second law. I have a box in which an egg rests inside. Egg is surrounded by some sort of padding. A force is applied to the box. (Force has an x and -y component. Are my conclutions right? 1) Force act on the box, not on the egg. Applying Newton's...
  47. J

    Newton's second law and D'Alembert's principle

    Newton's second law! According to Newton's second law if the resultant force acting on a body is non zero the body moves with an acceleration proportional to the mass of the body, right?Then, 1. Can anyone explain this in an intuitive sense? 2. In solving problems we say that the resultant...
  48. B

    Newton's Second Law: Example Explained

    I'm reading through an example involving Newton's second law. The situation is that there are n particles surrounded by a system boundary. The picture consists of a bunch of circles (particles) enclosed by a closed loop. The forces acting on one of the particles of mass m_i consist of an...
  49. D

    Newton's Second Law Explained - Learn the Basics

    Question answered! Thanks for the input!
  50. H

    Question: conservation of E and Newton's second law

    I was wondering if anyone had some input on how, via calculus, to show how the law of conservation of mechanical energy for an object in free fall (ideal) is a direct consequence of the of Newtons second law.
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