1 / 11

Circular Motion

Circular Motion. Principles of Physics. r. When an object moves in a circle its path is described by:   Radius (r) – distance from the center to the perimeter (meters) Circumference (C) – perimeter of circle (2πr) (meters)

zilya
Télécharger la présentation

Circular 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. Circular Motion Principles of Physics

  2. r When an object moves in a circle its path is described by:   Radius (r) – distance from the center to the perimeter (meters) Circumference (C) – perimeter of circle (2πr) (meters) Period (T) – time to go around the circle once (seconds)

  3. Rotational Speed vs Linear Speed Rotational Speed (scalar quantity) • number of times around the circle per unit time (rot/s) Linear Speed (v) • Distance per unit time

  4. Rotational Speed vs Linear Speed Example: An object is moving around a circle of radius 5m. It completes 5 rotations every second. How fast is it going?

  5. Centripetal Force • Assume linear speed (what the speedometer in your car would read) is not changing during motion in a circle • Speed is constant • Direction is changing • If velocity is changing then the object is accelerating • If the object is accelerating then an unbalanced force must be acting on it Changing Velocity

  6. Centripetal Force Remember: Newton’s 1st Law → objects in motion stay in motion in straight lines unless a force is acting So, A force must be acting on an object if it is travelling in along a circular path Special name – centripetal force (Fc) (centripetal = center seeking) **No such thing at centrifugal or centrifical force

  7. Centripetal Force • To move in circles the direction of the force is always changing, but always directed toward the center of the circular path. v • Fc, ac

  8. Centripetal Force Centripetal force is another name for any force that causes an object to move in circles Therefore, Any type of force can be a centripetal force Example: friction keeps cars moving around circular ramps when entering or exiting the highway.

  9. Calculating Centripetal Force We know: F = ma, so Fc = mac ac = centripetal acceleration = v2/r so, Fc = mac = mv2/r Fc = macac = v2/r Fc = mv2/r

  10. Example 1: A 1.0 kg ball attached to a string 0.50 m long is swung in a circle. Its speed along the circular path is 6.0 m/s. What are ac and Fc? m = 1 kg r = 0.5 m v = 6 m/s ac = v2/r = (6m/s)2 /0.5 m = 72 m/s2 Fc = mac = 1 kg (72 m/s2) = 72 N

  11. Example 2: Suppose a 5 kg object is being held in a circular path of radius 20 m with a force of 400 N. What is the speed of the object? Fc = mv2 r 400 = 5v2 20 400(20) = 5v2 5 5 1600 = v2 v = 40 m/s m = 5 kg r = 20 m F = 400 N

More Related