Download Circular Motion Web Quest

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.
Athletics
14. What is the most common example of the physics of circular motion in sports?
15. Does the motion of an athlete have to be a full circle to be considered circular motion? Explain.
16. For the speed skater depicted in the picture to the right, draw
Free Body Diagrams showing the two components of the contact
force.
17. Explain the interactions that occur between a skater and the ice
that enable a skater to move across the ice as they do.
18. A turn is only possible when there is a component of force directed
towards the ______ of the circle about which the person is moving.
19. 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.
20. 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:
21. 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. acceleration
b. Fg
c. Fn
d. Ff
e. angle of lean (Ө)
22. 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?
Newton’s Law of Universal Gravitation
12. Distance is not the only factor affecting gravitational force, what is the other?
13. “Gravity is Universal” …what does this mean?
14. Describe the following:
F ~ (m1m2)/d2
15. What is the equation used for universal gravitation? What does G represent? What is the value
of G?
16. 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?
17. 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?
18. What is the cause of this force which we refer to as gravity?
19. What variables affect the actual value of the force of gravity?
20. Why does the force of gravity acting upon an object depend upon the location of the object
relative to the Earth?
21. How does gravity affect objects which are far beyond the surface of the Earth?
22. How far-reaching is gravity's influence?
23. Is the force of gravity which attracts my body to the Earth related to the force of gravity
between the planets and the Sun?