Circular Motion Web Quest: Access the Web site listed below. Answer all questions completely and draw diagrams to aid explanations when applicable. http://www.physicsclassroom.com/Class/circles/index.cfm Lesson 1: Motion Characteristics for Circular Motion Speed & Velocity 1. What does the phrase Uniform Circular Motion suggest? Give an example other than the car example used in the web site. 2. Average speed is calculated by dividing distance by time. How is the speed of an object moving in uniform circular motion calculated? 3. This semester we have used “t” to represent time in equations. What does “T” represent? Explain what T signifies. 4. Do objects moving in uniform circular motion have constant speed? Constant velocity? Explain. 5. What term is used to describe the direction of a velocity vector? Why is this term used? Acceleration 6. Is an object moving in uniform circular motion accelerating? Explain. 7. Objects moving in circles at a constant speed accelerate towards the ___________ of the circle. 8. What is an accelerometer? 9. Which vector below represents the direction of the velocity vector when the object is located at point B on the circle?
10. Which vector below represents the direction of the acceleration vector when the object is located at point C on the circle? 11. Which vector below represents the direction of the velocity vector when the object is located at point C on the circle?
12. Which vector below represents the direction of the acceleration vector when the object is located at point A on the circle?
Centripetal Force 13. What is centripetal force? What does the term centripetal mean? 14. Why, when sitting as a passenger in a car that is making a circle (turn) to the left do you feel as if there is an outward acceleration or force when there really is an inward acceleration? Centrifugal Force 15. What does centrifugal mean? 16. Why is there so much misconception regarding centrifugal forces? 17. Does the sensation of being thrown outward from the center of a circle mean that there was definitely an outward force? 18. Click on the first animation button. Describe what is happening. Then do the same with the second animation button. Circular Motion Mathematics 19. List (in an organized fashion) and describe all equations in red. Read through the practice problems and then draw diagrams and show all steps as you answer the following questions: 20. Anna Litical is practicing a centripetal force demonstration at home. She fills a bucket with water, ties it to a strong rope, and spins it in a circle. Anna spins the bucket when it is half-full of water and when it is quarter-full of water. In which case is more force required to spin the bucket in a circle? Explain using an equation as a "guide to thinking." 21. A Lincoln Continental and a Yugo are making a turn. The Lincoln is four times more massive than the Yugo. If they make the turn at the same speed, then how do the centripetal forces acting upon the two cars compare. Explain. 22. The Cajun Cliffhanger at Great America is a ride in which occupants line the perimeter of a cylinder and spin in a circle at a high rate of turning. When the cylinder begins spinning very rapidly, the floor is removed from under the riders' feet. What affect does a doubling in speed have upon the centripetal force? Explain. 23. Determine the centripetal force acting upon a 40-kg child who makes 10 revolutions around the Cliffhanger in 29.3 seconds. The radius of the barrel is 2.90 meters.
Circular Motion Web Quest: Access the Web site listed below. Answer all questions completely and draw diagrams to aid explanations when applicable. http://www.physicsclassroom.com/Class/circles/index.cfm Lesson 2: Applications of Circular Motion Newton’s Second Law 1. Explain how Newton’s Second Law of Motion can be used to analyze the circular motion as shown in the photos below:
Read through the practice problems and then draw diagrams and show all steps as you answer the following questions: 2. 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. 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. Roller Coasters 4. Explain why is the thrill of a roller coaster due to the acceleration rather than the speed. 5. Draw individual diagrams to show the acceleration at points A, B, C & D of the diagram to the right: 6. An inward acceleration is caused by an __________ net force. 7. If friction and air resistance are ignored, what two forces will be experienced by a roller coaster car, or occupant?
8. Gravity always acts________ and the normal force always acts _______ to the track. 9. Sketch Free Body Diagrams for the coaster car when it is at the top and then at the bottom of a loop on the track. 10. Why will the rider on a roller coaster feel heavier at the bottom of a loop and lighter at the top of a loop. 11. Is it possible to experience free fall on a roller coaster? Explain. Read through the practice problems and then draw diagrams and show all steps as you answer the following questions: 12. Anna Litical is riding on The Shock Wave at Great America. Anna experiences a downwards acceleration of 12.5 m/s2 at the top of the loop and an upwards acceleration of 24.0 m/s2 at the bottom of the loop. Use Newton's second law to determine the normal force acting upon Anna's 50-kg body at the top and at the bottom of the loop. 13. Noah Formula is riding a roller coaster and encounters a loop. Noah is traveling 6 m/s at the top of the loop and 18.0 m/s at the bottom of the loop. The top of the loop has a radius of curvature of 3.2 m and the bottom of the loop has a radius of curvature of 16.0 m. Use Newton's second law to determine the normal force acting upon Noah's 80-kg body at the top and at the bottom of the loop. 14. Noah Formula is riding an old-fashioned roller coaster. Noah encounters a small hill having a radius of curvature of 12.0 m. At the crest of the hill, Noah is lifted off his seat and held in the car by the safety bar. If Noah is traveling with a speed of 14.0 m/s, then use Newton's second law to determine the force applied by the safety bar upon Noah's 80-kg body. 15. Anna Litical is riding a "woody" roller coaster. Anna encounters the bottom of a small dip having a radius of curvature of 15.0 m. At the bottom of this dip Anna is traveling with a speed of 16.0 m/s and experiencing a much larger than usual normal force. Use Newton's second law to determine the normal force acting upon Anna's 50-kg body. Athletics 16. What is the most common example of the physics of circular motion in sports? 17. Does the motion of an athlete have to be a full circle to be considered circular motion? Explain. 18. For the speed skater depicted in the picture to the right, draw Free Body Diagrams showing the two components of the contact force. 19. Explain the interactions that occur between a skater and the ice that enable a skater to move across the ice as they do. 20. A turn is only possible when there is a component of force directed towards the ______ of the circle about which the person is moving.
21. Any given physical situation can be analyzed in terms of the individual _____ which are acting upon an object; these individual forces must add up to the _____ force. 22. Read the “Suggested Method of Solving Circular Motion Problems” and write the steps in your own words (paraphrase). Read through the practice problems and then draw diagrams and show all steps as you answer the following questions: 23. A 55.0-kg softball player runs at 7.0 m/s around a curve whose radius is 15.0 m. The contact force (vector combination of the frictional force and the normal force) acting between the ground and the player's feet supply both the centripetal force for making the turn and the upward force for balancing the player's weight. Use a free-body diagram and your understanding of circular motion and Newton's second law to determine: a. b. c. d. e.
acceleration Fg Fn Ff angle of lean (Ө)
24. In the hammer throw, a sphere is whirled around in a circular path on the end of a chain. After revolving about five times the thrower releases his grip on the chain and the "hammer" is launched at an angle to the horizontal. A diagram of the athlete and the hammer is shown to the right. Assume that the hammer is moving in a circle in a horizontal plane with a speed of 27.0 m/s. Assume that the hammer has a mass of 7.30-kg and that it moves in a circle with a 1.25-m radius. Since the hammer is moving in a horizontal plane, the centripetal force is directed horizontally. The vertical component of the tension in the chain (directed upward) is balanced by the weight of the hammer (directed downward). Use the diagram and an understanding of vector components to determine the tension in the chain.
Circular Motion Web Quest: Access the Web site listed below. Answer all questions completely and draw diagrams to aid explanations when applicable. http://www.physicsclassroom.com/Class/circles/index.cfm Lesson 3: Universal Gravitation Gravity must be understood in terms of its cause, its source, and its far-reaching implications on the structure and the motion of the objects in the universe. Gravity is More Than a Name 1. Thoroughly differentiate between the force of gravity (Fg) and the acceleration due to gravity
(g). The Apple the Moon and the Inverse Square Law
2. Who was Johannes Kepler? Describe his three laws of Planetary Motion. 3. Who was Tycho Brahe? 4. What “bothered” Sir Isaac Newton about Kepler’s Laws? 5. What led Newton to his notion of Universal Gravitation? 6. Briefly explain the cannonball as launched from “Newton’s Mountain”. 7. To avoid hitting the Earth, an orbiting projectile must be launched with a speed of ____ .
8. What made Newton believe that gravity was “diluted” by distance? 9. What is meant by the following statement: “The force of gravity between the earth and any
object is inversely proportional to the square of the distance which separates that object from the earth's center.” 10. Describe the following:
Fg ~ 1/d2
11. Suppose that two objects attract each other with a gravitational force of 16 units. If the distance
between the two objects is doubled, what is the new force of attraction between the two objects? 12. Suppose that two objects attract each other with a gravitational force of 16 units. If the distance
between the two objects is tripled, then what is the new force of attraction between the two objects? 13. Suppose that two objects attract each other with a gravitational force of 16 units. If the distance
between the two objects is reduced in half, then what is the new force of attraction between the two objects? 14. Suppose that two objects attract each other with a gravitational force of 16 units. If the distance
between the two objects is reduced by a factor of 5, then what is the new force of attraction between the two objects? 15. Having recently completed his first Physics course, Noah Formula has devised a new business
plan based on his teacher's Physics for Better Living theme. Noah learned that objects weigh different amounts at different distances from Earth's center. His plan involves buying gold by the weight at one altitude and then selling it at another altitude at the same price per weight. Should Noah buy at a high altitude and sell at a low altitude or vice versa? Newton’s Law of Universal Gravitation
16. Distance is not the only factor affecting gravitational force, what is the other? 17. “Gravity is Universal” …what does this mean? 18. Describe the following:
F ~ (m1m2)/d2
19. What is the equation used for universal gravitation? What does G represent? What is the value
of G? 20. Suppose that two objects attract each other with a gravitational force of 16 units. If the distance
between the two objects is doubled, what is the new force of attraction between the two objects? 21. Suppose that two objects attract each other with a gravitational force of 16 units. If the distance
between the two objects is reduced in half, then what is the new force of attraction between the two objects? 22. Suppose that two objects attract each other with a gravitational force of 16 units. If the mass of
both objects was doubled, and if the distance between the objects remained the same, then what would be the new force of attraction between the two objects? 23. Suppose that two objects attract each other with a gravitational force of 16 units. If the mass of
both objects was doubled, and if the distance between the objects was doubled, then what would be the new force of attraction between the two objects? 24. Suppose that two objects attract each other with a gravitational force of 16 units. If the mass of
both objects was tripled, and if the distance between the objects was doubled, then what would be the new force of attraction between the two objects? 25. Suppose that two objects attract each other with a gravitational force of 16 units. If the mass of
object 1 was doubled, and if the distance between the objects was tripled, then what would be the new force of attraction between the two objects? 26. As a star ages, it is believed to undergo a variety of changes. One of the last phases of a star's
life is to gravitationally collapse into a black hole. What will happen to the orbit of the planets of the solar system if our star (the Sun shrinks into a black hole)? (And of course, this assumes that the planets are unaffected by prior stages of the Sun's evolving stages.) 27. What is the cause of this force which we refer to as gravity? 28. What variables affect the actual value of the force of gravity? 29. Why does the force of gravity acting upon an object depend upon the location of the object
relative to the Earth? 30. How does gravity affect objects which are far beyond the surface of the Earth? 31. How far-reaching is gravity's influence? 32. Is the force of gravity which attracts my body to the Earth related to the force of gravity
between the planets and the Sun?
