Forces 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. E

    Forces of Attraction in different states of matter.

    We are taught that the forces of attraction in a liquid are lesser than those in a solid. What is the reason? Is it because the intermolecular spaces are large or is it because the individual attractive force of the molecule is less?
  2. defaultusername

    Is the Tension Force in an Atwood Machine Only Transmitted Between Blocks?

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  3. S

    Questions about understanding circular motion & the forces involved

    Hey, I'm having some difficulty in understanding circular motion and it's forces. Here is the situation I'm on: Imagine you are on a smooth turn-table with smooth shoes and the table starts spinning. Because of inertia, and because the frictional force is not nearly enough to keep you going in a...
  4. J

    Motion with elastic potential energy and other forces

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  5. Zoey

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  6. jeisson botache

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  7. kolleamm

    B Eroding Metal with very small forces

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  8. H

    Prove forces derived from a velocity-dependent potential are not central

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  9. J

    What is the tension supporting one ball?

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  10. S

    How Does Gravity Vary Inside the Earth?

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  11. JulienB

    Pendulum and constraining forces (Lagrangian mechanics)

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  12. IMadeYouReadThis

    I Best way to create artificial forces

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  13. C

    Having trouble calculating reaction forces for this truss.

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  14. S

    Why do conservative forces MUST depend on the position?

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  15. Evangeline101

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  16. T

    Block Placed on Top of Another Block - Finding Max Force

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  17. F

    I Sum of internal forces equals zero

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  18. physea

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  19. Biker

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  20. E

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  21. M

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  22. G

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  23. J

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  24. L

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  25. C

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  26. V

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  27. ramzerimar

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  28. E

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  29. E

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  30. B

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  31. nso09

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  32. E

    Name of the forces caused while driving a car

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  33. S

    Forces that cause acceleration due to conservation laws

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  34. B

    What forces causes the top book to accelerate horizontally?

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  35. komarxian

    Calculating Electrical Force on Alpha Particle Near Gold Nucleus

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  36. K

    I Simple Fulcrum Force Calculation Question

    Hello all, I have a (at what first seemed) fairly simple question about calculating the forces on this fulcrum design I have. Here is an image of the sketch and free body diagram that I drew: Basically, the pivot point in my real life application is actually a cam, but for the sake of this...
  37. Blockade

    Are the sum of all forces written correctly for this system?

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  38. Blockade

    Can someone check if this centripetal force is correct?

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  39. Blockade

    Can someone check if this forces problem on an incline

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  40. Blockade

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  41. Blockade

    Can someone help me find the angle between two forces?

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  42. S

    Double pulley Atwood machine (with 3 masses)

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  43. Z

    Forces - Concerning Spindles with Out of Balance Loads/Help

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  44. B

    How Do You Calculate Tension in a Rope Pulling a Box with Friction and an Angle?

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  45. S

    Rotational work and forces like static friction and tension

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  46. S

    Why do conservative forces try to reduce potential energy?

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  47. faradayscat

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  48. I

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  49. I

    What are the forces acting on a child pulling a wagon up an inclined hill?

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  50. E

    Work function of conservative forces

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