Circular Motion and "Other" Applications of Newton's Laws
Centrip'n Practice Deluxe
Side A #4
Side A #5
Side A #6
6.3
7E
ERF
6 m
Side B #2
Side B #3
Side B #4
Circular
­tion
­al
and
Forces
Instructions: Free­body diagram each situation below and identify the force acting as the centripetal force.
#1 A ball bearing on a string whirled around in "deep space".
#3 Car makes a right turn to miss a deer in road.
#5 Roller coaster does a loop.
#2 Einstein makes a right turn on his bike.
θ
#4 Car makes a banked left turn.
#6 The ERF orbits the sun. #1
A ball bearing on the end of a string is whirled in a circle in "deep space". If the mass of the BB is 0.1 kg, and it travels at 7 m/s at the end of a string that is 1.3 m long...
a) What is the tension in the string?
b) What is the magnitude of the centripetal force acting on the BB?
c) What is the direction of the centripetal force?
#2
If the string in problem #1 were only strong enough to withstand 12 N of force before breaking, what is the maximum speed that the BB could go before the string breaks?
#3
A Bugatti Veyron (1888kg) drives around a circular track with a radius of 300 m. At the moment the driver sees that the speedometer reads 200 mi/hr, what force must the road exert on the tires to keep the car from spinning out? #4
In an episode of CSI Miami a centrifuge is used to spin a test tube filled with blood. The devise spins the tube in a circle of 18 cm radius at a speed of 11 revolutions per second. a) What type of force is acting as the centripetal force in this case?
b) What force is exerted on a 0.1 gram blood clot particle in the tube?
#5
A 1.3 g cockroach stands on the edge of a 12 in diameter LP record album. The turntable spins the record at the standard LP speed (Google It!). a) What coefficient of friction is needed to keep the roach from slipping off?
b) Would the answer be different if the roach in the story were replaced with a more massive giant roach?
BONUS BUGATTI PROBLEM:
The Veyron from problem #3 takes a banked freeway exit ramp at 50 mi/hr. If the radius of the ramps curvature is 285 ft, what angle should the ramp be tilted so that the car can make the turn even on a day when the road is extremely icy (μ ≈ 0)?
Circular Motion MC Extravaganza
Intructions: Choose the best answer AND justify the choice with math and/or physics logic statements.
7.
The Law of Universal Gravitation
The Law of Universal Gravitation
Universal Gravitational Constant
Some Very Attractive Problems
#1 Pretend you are sitting in the front row of a Justin Bieber concert. Are you attracted to him?
(We are talking about gravitational attraction. We make no judgments here in physics class.)
YES
NO
#2 Calculate the force of attraction between you and the Biebster. Estimate your masses to be 70 kg, and the distance between you to be 5 m.
#3 How much would The Bieb have to weigh (in pounds) in order for the force of attraction between you to reach one Newton?
With this bitchin hair, I could have been a baller like Bieber!
#4 After the concert, you go home to your sad little life while Justin hops in his Lear Jet and flys off to another city across the globe. Are you still attracted to him? (Gravitationally)
YES
NO
#5 Did you cry just a little when he left town?
YES
NO
#6 Be Honest...Have you ever had the Baby Baby Oh song stuck in your head?
YES
NO
*I bet is is now...AHHHHHHAHAHAHAHAHA!...Like Baby Baby Oh!
Sumo Attractive Problems
a) Fg = 2.3E­7 N
b) asumo = 1.15E­9 m/s2 , astud = 4.6E­9 m/s2 ∴ astud = 4 times asumo
c) fmax = 392 N ∴ asumo = ZERO!
Circular Motion and Universal Gravity Pre­Quiz Spectacular On Ice
#1 WWBBD?
Brian Boitano (165 lb) executes a constant speed circular turn to his right during a skating performance as part of the CBS Special... "Ex­Olympians that Still Need a Pay­Check Salute to the Armed Forces in a Non­Denominational Holiday Spectacular on Ice".
a) Draw a Free­Body diagram of Brian...
b) Identify which force is acting as the centripetal force.
c) Brian's speed is 4 m/s and the circle has a diameter of 6 m. What is the magnitude of his centripetal acceleration?
d) What is the coefficient of friction μ?
e) If Brian were to double his speed, but keep the size of the turn the same, what would happen to the centripetal force?
#2 Brian and ex­Olympian/Dancing with the Stars contestant Apolo Ohno (145 lb) stand on the ice 2 m apart, what is the force of gravitational attraction between them? #3
If both skaters eat enough sumo food (Chankonabe: fatty­
meat,cabbage, and egg soup) to quadruple in mass, and the distance between them is doubled, the force of attraction would...
a) double
b) triple
c) be cut in half
d) be one fourth as much
e) quadruple
f) remain unchanged #4
If the ice rink has the usual amount of friction, would the ex­
Olympians accelerate toward each other due to the gravitational attraction between them?
a) No, because the attraction is way too weak.
b) Yes, but very very very slowly.
c) No, they would accelerate away from each other because friction is the greater force.
d) Yes, because gravity is stronger than friction...F=ma!
#5 A star is seen in a deadly dance around a black hole. If the radius of the orbit is 5E7 m, and the period of the rotation is 40 sec, a.) What is the mass of the black hole in kg?
b.) What is it expressed in solar masses?
(Msun = 2E30 kg)
On the Circular Motion/Univ. Gravity quiz A+SSBAT...
•
Sketch free­body diagrams for situations where objects are turning, and identify what is acting as the centripetal force. (See the Centripetal Force Lab and the front of the Centipede worksheet) •
Understand that the definition of acceleration includes a change in the direction of an objects motion
(centripetal acceleration) even though it's speed does not change, and that this requires a real force directed toward the center of the turn (centripetal force). •
Combine the equations of circular motion with the correct "special force" equation to solve multiple choice questions and story puzzles for scenarios where an object is undergoing circular motion. (See the back of the Centipede worksheet, and the Centrip'n Practice sheet)
•
Use the law of Universal Gravity to determine the force of attraction between objects, and then use that result along with Newton's 2nd law to predict the acceleration of those objects. (See the Gravity Sim Lab, the Justin Bieber sheet, and the Sumo sheet)
•
Combine the equations of circular motion with the law of Universal Gravity to solve multiple choice questions and story puzzles about orbital motion.(See; Some More Universally Attractive Problems, the Univ. G/Orbital Motion MC Extravaganza)
•
Understand the basic physics of the Coriollis Effect, Geo­synchronous Satellites, and Black Holes.
(See the bonus problem on Some More Universally Attractive Problems, Adam Goes Shopping, and Black Holes video Q's)
Newton's Laws of Motion 1st Law: Inertia
2nd Law: Static Equilibrium
Kinematics
Kinematics
3rd Law: Action/Reaction
Dynamics
Linear Dynamics
Circular Motion
1­Dimensional
2­Dimensional
(projectile Motion)
Special Forces
erf
Weight
Orbital Motion
Friction
Springs
The Johannes Brothers
Gravitation
I partied
with that guy