Force Definition and 1000 Threads

In physics, a force is any influence that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newton (N). Force is represented by the symbol F (formerly P).
The original form of Newton's second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time. If the mass of the object is constant, this law implies that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object.
Concepts related to force include: thrust, which increases the velocity of an object; drag, which decreases the velocity of an object; and torque, which produces changes in rotational speed of an object. In an extended body, each part usually applies forces on the adjacent parts; the distribution of such forces through the body is the internal mechanical stress. Such internal mechanical stresses cause no acceleration of that body as the forces balance one another. Pressure, the distribution of many small forces applied over an area of a body, is a simple type of stress that if unbalanced can cause the body to accelerate. Stress usually causes deformation of solid materials, or flow in fluids.

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  1. L

    I Not a physics major -- Question about how far we can kick an object

    Currently debating with friends how far varying weighed objects could be punted and the distance we could kick them. Instead of grabbing dumbbells I'd rather use math. Was looking for an equation to use and have been having trouble. I know the average adult can kick with a force of 1000lbs...
  2. H

    Explain why applying different forces to objects of different masses result in different accelerations

    I don't really get why applying different forces to objects of different masses would result in different accelerations. I read my textbook, and I understand the formula F(net) = m*a, and I think the reason may be because mass is inversely proportional to acceleration ? But this doesn't really...
  3. Sat-P

    Electromagnetic force on a positively charged particle

  4. Nabir14

    B Is there any physics topic explaining how objects break into parts?

    I am curious to know if there is any existing topic explaining how objects break into several pieces when force is applied.
  5. dlucaswood

    B Force required to stretch training resistance bands

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  6. R

    B Compressive force of a shorter cylindrical bone vs a longer one

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  7. Quantum55151

    I Mechanics of an inertial balance

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  8. tellmesomething

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  9. Heisenberg7

    Applying Force on a Cylinder at an Angle

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  10. A

    How Do You Calculate Component Forces in an Automotive Drum Brake?

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  11. B

    Textbook 'The Physics of Waves': Calculating Work Done by Force

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  12. P

    I Producing enough force with a Solenoid

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  13. S_Subramaniam

    General question about the definition of moment of force (Torque)

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  14. N

    Reference source of study for welding clamping force calculation

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  15. Hauzen

    Engineering explanation please (pipe welded to a wall)

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  16. Hauzen

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  17. S

    B What is electromotive force? What's its relationship to Voltage?

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  18. chwala

    What Force must be exerted on the trolley for constant speed?

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  19. Bling Fizikst

    Force between charged particle and conducting cylinder

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  20. P

    Shape of Slinky being twirled in 0 gravity

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  21. Iwawa48

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  22. D

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  23. AmanWithoutAscarf

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  24. tellmesomething

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  25. PhysicsEnjoyer31415

    I Equality of Gravitational and Electrostatic force

  26. chwala

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  27. Username34

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  28. highschoolstudent454

    B Is the time derivate of force equal to the position derivative power?

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  29. K

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  30. dannolul

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  31. P

    Calculate electric force using Coulomb's law (vector components are the struggle)

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  32. rosedog09

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  33. Lotto

    B What forces act on a bar when you do pull-ups?

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  34. S

    Minimum force to tip the bin over

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  35. R

    B How to convert ft-lbs/sec to Newtons?

    Hi, How to convert 51065 foot pound per second to Newtons, not Newtons meter per second?
  36. tharindu_

    B Why don't cars accelerate according to F = ma?

    If the engine is constant, then the wheels of the car exerts a constant force on the floor. And F = ma, So the car should be accelerating rather than maintaining the same speed. What is going on here?
  37. WeirdUniverse

    I The answer for the total mass of the Universe?

    it requires less energy to impart acceleration to an object than to the entirety of the universe, This would break the principle of relativity since the amount of energy to move an object should be the same as the amount of energy to move the rest of the universe. This observation implies a...
  38. hello478

    Graph of viscous force and velocity

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  39. Sam Jelly

    Center of mass acceleration for an inclined plane and mass m

    Why is the center of mass acceleration zero? Did I do anything wrong?
  40. hello478

    Minimum work done to push the cube over

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  41. cestlavie

    Why Isn't the Spring Force Sum of Both Ends?

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  42. hello478

    Horizontal force by block on a beam

  43. hello478

    Horizontal force on hinge is affected by moving the block farther away?

    my attempt: no effect
  44. I

    Centripetal force - Ferris wheel... Opposite results

    I don't understand why am I getting opposite answers. I get 250N for the lowest point and 750 for the highest point. For the highest point: ##F_{net}=F_{cp}+F_{mg}-F_N## and then ##F_N=ma_{cp}+mg = 50*(25/5)+500=750N## because I've been told that ##F_{cp}## always acts towards the center of the...
  45. Mitchell Richardson

    Finding force between solenoid and magnet

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  46. G

    I Force between opposing magnets

    Following a conversation with @Tom.G , I’ve come up with the following question, to which we’d both like an answer: Imagine two drilled magnets threaded onto a frictionless upright shaft, set N-N. One fixed down, the other floating above. Now, if I move an iron gate in and out of the gap (the...
  47. P

    Estimating the force exerted by a water jet on a flat plate - Bernoulli vs Momentum Equation

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  48. M

    Does a Slowing Piano Exert More Force Than the Man Pushing It?

    Albeit the simple question, I am a bit confused on whether the correct answer choice is (B) or (C). When the piano is slowing down, shouldn't the force received by the piano be a bit greater than the force received by the man?
  49. Mohmmad Maaitah

    How Does Stress Affect a Hollow Pipe When Force Is Uniformly Applied?

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  50. mister i

    B Can the force of gravity overcome the Planck force?

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