What is Force: Definition and 1000 Discussions

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. S

    Solving for weight and mass in kg in an elevator

    Fn= normal force W=mg W=(65)(9.8)= 637N Fn-637= -(65)(0.2*9.8) Fn= 509.6N I got the weight of the woman in the elevator, but I have trouble finding what the scale reads in kg. I was given the solution which read: a = (g-0.2g)= 0.8g W= 0.8g*509.6N= 52kg. My questions 1. why do I have to...
  2. M

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  3. Meruem

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  4. Meruem

    B Is quantum entanglement a four dimensional force?

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  5. M

    Undergraduate physics: Body flows inside liquid [ v(x)=? and V(lim)=? ]

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  6. D

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  7. K

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    Let's say we are in outer space.Suppose I have 2 metallic balls A and B with initial velocity 0 and same mass M and a baseball bat.Let's say I hit the ball A with force F and ball B with F' in such a way that F>F'.Ball A attain final velocity V in time T and ball B attain final velocity V' in...
  8. Snarlie

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  9. FQVBSina

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  10. M

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  11. J

    I Can we increase an object's gravitational force by adding energy?

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  12. J

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  13. colcol500

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  14. vivek_salman

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  15. N

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  16. S

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  17. patricio ramos

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  18. L

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  19. warhammer

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  20. H

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  21. F

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  22. I

    Forces along non-perpendicular axes

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  23. A

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  24. A

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  25. Kaitlynn Robicheaux

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  26. Shashwat02

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  27. A

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  28. F

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  30. mgkii

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  31. harsh22902

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  32. T

    I How to Calculate the force to push a wheelchair up a ramp?

    How do I calculate the required push force (in kgf) for pushing a wheelchair up a ramp? - the ramp has a 5 degree incline - the weight of the chair and person in it totals 96.8 kg - the wheelchair has 4 wheels, all of equal diameter (15 cm) - the wheels on the wheelchair have a rolling...
  33. jisbon

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  34. bob012345

    Does matter exert a Force on Fields (or Light)?

    In a simple example of two current carrying wires, there are mutual forces. Do we speak of the forces on each wire as action-reaction or as someone I'm debating with, each wire and the fields from the other wire as action-reaction? Or both? Thanks.
  35. bob012345

    I Force on Photon? Interaction with Matter Explained

    When photon interact with matter there is a force. Do we speak in terms of Newtonian action-reaction? When a photon exerts a force on matter -an action- do we speak of a force on the photon - a reaction? Thanks.
  36. E

    Why have a feed force in the cutting process?

    You knew there is a cutting force in the orthogonal process, it is exerted by cutting speed, buy why have a feed force?
  37. M

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    Summary: 55 gallon drum weighing 518 pounds is tipped over. How much force is needed to upright the tipped drum? I am an environmental, health and safety professional in the food manufacturing industry. We recently had two employees that came upon a 55 gallon drum that was tipped over. The...
  38. SebastianRM

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    I was reviewing physics stuff and I've managed to confuse myself. I was reading about work (principles of ohysics, serway&jewtt): -work is an energy transfer -if work is done on a system and W is positive, energy is transferred to the system; if W us negative, energy is transferred from the...
  39. F

    I Is there a violation in logic when we define notions of mass and force?

    Which part of Newton's second law is definition and which part is law content?It seem that there is a violation in logic, because we define the notion of force through the notion of mass, then we define the notion of mass through the notion of force when we consider the second law.
  40. F

    I Do action force and reaction force lie on same line?

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  41. adamaero

    Understanding Electric Force on Q in Relation to Distance d and Charge Q1

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  42. Ranstor

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  43. R

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  44. K

    B Is Gravity a Force? - Exploring Relativity

    Hi all, another newbie question for you. I often hear gravity described as a force, including speculation that gravitons are its messenger particle, but is that consistent with general relativity? I thought relativity implies it's more like rolling down a hill than being pulled by a force.
  45. M

    Centripetal Force: What Happens When Force Increases?

    Suppose, there is an object in a circular path that goes with a cirtain speed. What happens, if suddenly the centripetal force increases? a) The object remains in the path but its speed increases b) The object exits the circular path c) Any other situation Please, explain your answer, thanks
  46. S

    Direction of the net force acting on a pendulum

    I imagine y - axis is parallel to direction of A and x - axis is parallel to direction of E. There are two forces acting on the pendulum: tension in direction of A and weight in direction of D. I break the weight into 2 components: W sin θ in opposite direction to tension and W cos θ in...
  47. C

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    Summary: How would you calculate the force at a point of a falling 220kV Conductor? Hi, bit a of a funny one. I need to calculate the force of a cable falling at a point (left edge of a scaffold) as detailed in the attached sketch. (Not to scale what so ever). We’re building a scaffold between...
  48. E

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    I require to calculate acceleration of an object caused by a force of 100N acting upon it. The weight of the object is 0.5kg I'm using the equation F = m * a Is it correct to use weight of the object instead of mass in the equation. Will it yield correct results? Or would I need to calculate...
  49. J

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  50. A

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