Aim: How do we explain centripetal motion?

Checkpoint 1- Newton’s 2nd Law Revisited A 1.50-kg bucket of water is tied by a rope and whirled in a circle with a radius of 1.00 m. At the bottom of the circular loop, the speed of the bucket is 6.00 m/s. Determine the acceleration, the net force and the individual force values when the bucket is at the bottom of the circular loop.

Checkpoint 2-Newton’s 2nd Law RevISITED A 1.50-kg bucket of water is tied by a rope and whirled in a circle with a radius of 1.00 m. At the top of the circular loop, the speed of the bucket is 4.00 m/s. Determine the acceleration, the net force and the individual force values when the bucket is at the top of the circular loop.

3. Turn and Talk Rotating Circular room A person rides in the rotating circular room ride and becomes stuck to the wall. Draw and label the forces acting on the person. Identify what force supplies the centripetal force. What conditions are necessary for person to not slide down wall?

4. Car on a hill Grandma has a mass of 50 kg and rides in a car over a hill of radius 5 m. At what speed will grandma loses contact with her seat at the top of the hill? Draw a freebody diagram showing all the forces acting on grandma when she is on top of the hill. Express the centripetal force in terms of other forces

Reading passage Uniform circular motion can be described as the motion of an object in a circle at a constant speed. As an object moves in a circle, it is constantly changing its direction. At all instances, the object is moving tangent to the circle. Since the direction of the velocity vector is the same as the direction of the object's motion, the velocity vector is directed tangent to the circle as well. The animation at the right depicts this by means of a vector arrow. An object moving in a circle is accelerating. Accelerating objects are objects which are changing their velocity - either the speed (i.e., magnitude of the velocity vector) or the direction. An object undergoing uniform circular motion is moving with a constant speed. Nonetheless, it is accelerating due to its change in direction. The direction of the acceleration is inwards. The animation at the right depicts this by means of a vector arrow. The final motion characteristic for an object undergoing uniform circular motion is the net force. The net force acting upon such an object is directed towards the center of the circle. The net force is said to be an inward or centripetal force. Without such an inward force, an object would continue in a straight line, never deviating from its direction. Yet, with the inward net force directed perpendicular to the velocity vector, the object is always changing its direction and undergoing an inward acceleration.