120 likes | 266 Views
Uniform Circular Motion. Homework: Read pages 153 – 156 P 156 Answer questions: 12, 13, 14, 15. Definition: the motion of an object in a circular path with a constant speed. When does this happen?. Driving a car at constant speed around a circular corner OR.
E N D
Uniform Circular Motion Homework: Read pages 153 – 156 P 156 Answer questions: 12, 13, 14, 15 Definition: the motion of an object in a circular path with a constant speed
When does this happen? • Driving a car at constant speed around a circular corner OR
Speed in a circular path Recall: to find speed V = distance / time for a circular path d = 2 p r the time required to complete one full revolution is called the period (T) Therefore, v = 2pr / T
Constant speed, but what about velocity? • Velocity of an object undergoing UCM is always directed tangent to the circular path • Direction is constantly changing, velocity is not constant • Therefore, the object must be accelerating
Centripetal Acceleration • Acceleration experienced by an object moving in a circular path at a constant speed. • Directed to the center of the circular path • centripetal means “center seeking” ac = V2 / r
Centripetal Force • Force directed toward the center of the circular path • Causes the centripetal acceleration Fc = m ac
Do Now Assume that the moon orbits the Earth in a circular orbit in 27.32 days. Using the List of Physical Constants on your Reference Tables, calculate the following: • the speed of the moon in its orbit. • the centripetal acceleration experienced by the moon • the centripetal force that keeps the moon in its orbit.
The answers: • V = 1022 m/s • ac = 0.00272 m/s2 • 2.0 x 1020 N