1 / 16

Forces and Newton’s Laws of Motion

Forces and Newton’s Laws of Motion. Forces. The natural state of an object –its behavior if free of external influences - is uniform motion with constant velocity. “At rest” has no special significance in Galileo’s view of motion.

kynan
Télécharger la présentation

Forces and Newton’s Laws of Motion

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Forces and Newton’s Laws of Motion

  2. Forces • The natural state of an object –its behavior if free of external influences - is uniform motion with constant velocity. • “At rest” has no special significance in Galileo’s view of motion. • Influences that lead to deviations from uniform motion are called forces.

  3. Newton’s First Law of Motion • Consider an object with no force acting on it. If it is at rest, it will remain at rest; • If it is moving, it will continue to move in a straight line at constant speed. • Consider the crash test dummy who continues in motion after the car has hit a wall. Always wear your seat belt! It’s just good physics!

  4. Properties of forces • A force is a push or pull • A force acts on an object. Forces do not act in isolation. • A force requires an agent. An agent is something that pushes or pulls. It can be an inert object • A force is a vector with magnitude and direction. The size or strength of the force is its magnitude.

  5. Properties of forces cont. • A force can be either a contact force or a long range force. • Contact forces are forces that act on an object by touching it at a point of contact (ex. Bat must hit ball to hit it) • Long range forces are forces that act on an object without physical contact (ex. Gravity or a magnet)

  6. Forces • In general the object exerts a force back on the agent. • A force is really an interaction between two objects

  7. Drawing force vectors

  8. Drawing force vectors • FN is the normal force. Normal means perpendicular. • Include what is being acted on, by what. (object and agent) FN Fgon the box by the earth

  9. More Force Drawings • Forces can represent a push or pull. Either way they are depicted the same, acting on a particle

  10. Combining Forces • The mathematical sumation is called the superposition of forces. The net force is the resultant. • FNET is not a new force – The original forces are replaced by FNET.

  11. What is the net force?

  12. Net force

  13. Stop to Think • Two of the three forces exerted on an object are shown. The net force points directly to the left. Which is the missing third force? • C

  14. Balanced Forces • Forces are balanced if the object is • Not moving or • At constant velocity

  15. Unbalanced Forces • Forces are unbalanced if • The object starts moving • The object changes direction • The object stops If there is an unbalanced force an object will accelerate

  16. Inertia • Inertia is an objects tendency to resist a change in motion • Remember the crash test dummy

More Related