Definition of Force

1. Definition of Force Drawing the Force Dimensions and Units of Force Tension Elastic Force Gravity Normal Force Friction Drag Pulleys

2. Force That which causes a particle to accelerate. It is a vector! Knight’s Definition A force … is a push or a pull on an object. It is a vector. It has both magnitude and direction. It requires an agent. Something does the pushing or pulling. It is either a contact force or a long-range force (gravity).

3. Force, like any vector is drawn as an arrow with the symbol or magnitude and units. The tail of the force is placed on the part of the object that is experiencing the force. In a free-body diagram, the tail is placed on the point representing the particle. The direction of the force and its magnitude are determined by the type of force it is.

4. Force The SI unit of force is the Newton (abbreviated as N). One Newton is the same as one kilogram-meter per second squared. Another unit of force is the pound.

5. Tension The magnitude of the tension is the same everywhere in the rope.

6. Tension If an object that is experiencing the force is pulling but not stretching another object On the object that is experiencing the force at the point where the pulling occurs Determined using Newton’s Second Law Toward the center of the object being pulled (rope, wire, etc.) No associated energy

7. Spring Force

8. Spring Force If an object that is experiencing the force is stretching (or compressing) another object On the object experiencing the force where it connects to the object that stretches/compresses Toward the center of the object that stretches or away from the center of the object that compresses Elastic Potential Energy

9. Gravity

10. Gravity or If there are two massive objects present At the center-of-mass of the object receiving the force or Toward the center of mass of the other massive object Gravitational Potential Energy

11. Gravity (near the earth’s surface) m Mass of the earth 6x1024 kg Radius of the earth 6.375x106 m

12. N m Normal Force N m w

13. Normal Force or If an object touches the surface of another object On the object receiving the force at the point(s) where it touches the surface Determined using Newton’s Second Law Perpendicular to the surface and from the object exerting the force to the object experiencing it No associated energy

14. N f m Direction of motion or possible motion Friction N f m Direction of motion or possible motion

15. Friction or If an object touches the surface of another object On the object receiving the force at the point(s) where it touches the surface or In a direction that opposes the motion or the possibility of motion Thermal Energy

16. Drag D

17. Drag If an object is moving through a liquid or gas. On the object receiving the force at the point(s) where it touches the liquid or gas In a direction that opposes the motion Thermal Energy

18. Pulleys Pulleys simply change the DIRECTION of a force. T T

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