(a) (b) FIGURE P7.81
Q: You are sparring in a tae kwon do class. Your opponent executes a roundhouse kick. The average…
A:
Q: A figure skater has a moment of inertia of 0.39 kg-m2. He is spinning at 251.6 rpm. He extends his…
A:
Q: A bicycle with 0.80-m-diameter tires is coasting on a level road at 5.6 m/s. A small blue dot has…
A:
Q: Casting of molten metal is important in many industrial processes. Centrifugal casting is used for…
A:
Q: Sarah and Tom are riding on a merry-go-round revolving with a constant angular velocity. Sarah is…
A: Option A: They have different linear speed but the same angular velocity
Q: A solid, uniform, spherical boulder ( I = 2/5 MR^2 ) starts from rest and rolls down a 50.0 [m]…
A: SOlution: height h = 50 m
Q: Your roommate is working on his bicycle and has the bike upside down. He spins the 54.0 cmcm…
A: a) The expression for find speed of the pebble is v=rω=d22πf Substitute values in the above equation…
Q: The diver illustrated in the Figure undergoes both translational and rotational or general motion.…
A: For this motion, The x-component of velocity is, vx=ltvcosθ=52.5vcosθ=2 .......(i) The…
Q: A fairground ride (The Gravitron) spins its occupants inside a cylinder-shaped container. A child on…
A: Given data Mass of the child, m=50 kg Radius of the circular path, r=8 m
Q: An 8.0-cm diameter hard disk spinning at 7200 rpm can stop in 19 revolutions. a) What is the…
A:
Q: A rock tied to the end of string swings at a constant angular rate. You measure the rock to pass…
A: Given data: Angular displacement (θ) = 10π radians Time (t) = 5.30 seconds Length of the string (L)…
Q: David is getting ready to take down the mighty Goliath. David ties a 583 g rock to a rope that is…
A: Given:Mass of the rock = 583 gLength of the rope = 2.3 mInclination of rope below the horizontal =…
Q: A solid sphere is released from the top of a ramp that is at a height h1 = 2.00 m. It rolls down the…
A:
Q: A common carnival ride, called a gravitron, is a large cylinder in which people stand against the…
A: Given Radius of the cylinder (r) = 15 m Friction μs = 0.54
Q: 4. A point object of mass 2m is attached to one end of a rigid rod of negligible mass and length L-4…
A: Initial momentum = mv = 30 m (Kg m/s)Using conservation of momentum30m…
Q: A 148 g ball is released from rest H = 1.51 m above the bottom track. It rolls down a straight 45°…
A:
Q: Suppose a circular disk is rotating at a rate of 60 revolutions per minute. a) Determine the angular…
A:
Q: The earth’s radius is about 4000 miles. Kampala, the capital of Uganda, and Singapore are both…
A:
Q: figure skater is spinning with her arms outstretched. She completed 4 full revolutions in 2 seconds.…
A:
Q: A 10,000 kg satellite is orbiting planet A, which has a mass of 8.68 x 10^25 kg. The satellite is…
A:
Q: The angular speed of a rotating platform changes from ω0 = 3.6 rad/s to ω = 6.4 rad/s at a constant…
A: Write the expression for centripetal acceleration.
Q: hile sitting in physics class one day, you begin to ponder the workings of the analog clock on the…
A:
Q: A 45 kg figure skater is spinning on the toes of her skates at 0.50 rev/s. Her arms are…
A:
Q: A barbell spins around a pivot at its center at A. The barbell consists of two small balls, each…
A: Given : Mass (m) = 500 g = 0.5 kg Length (d) = 30 cm = 0.3 m Radius (r) = 0.15 m Angular speed (w) =…
Q: A child is riding a merry-go-round which completes one revolution every 8.36 s. The child is…
A: Write the expression for angular speed of the merry-go-round.
Q: A 5 kg hoop (I=MR2) with a radius of 2 m is placed at the top of a hill that is 8 m high. There is…
A: Using conservation of energy,
Q: When some stars use up their fuel, they undergo a catastrophic explosion called a supernova. This…
A: Given:Radius of a star = RRadius of supernova shell = 3.9RNumber of revolutions of star per day =…
Q: A baseball pitcher throws a baseball horizontally at a linear speed of 42.5 m/s. Before being…
A:
Q: A 0.500-kg ball that is tied to the end of a 1.50-m light cord is revolved in a horizontal plane…
A: The free-body diagram of the ball is,
Q: A merry-go-round is a common piece of playground equipment. A 3.0-mm-diameter merry-go-round, which…
A: The objective of the question is to find the angular velocity of the merry-go-round after John jumps…
Q: A 5 kg disk with a radius of 20 cm is spinning at 20 rpm. A clump of clay is dropped on the edge of…
A:
Q: A large wind turbine (typical of the size and specifications of a turbine that you see in a modern…
A:
Q: A rotating table, with moment of inertia 29 kg·m2, is spinning at 40 rpm. A piece of clay is dropped…
A:
Q: A 45 kg figure skater is spinning on the toes of her skates at 0.60 rev/s. Her arms are outstretched…
A: Using the conservation of Angular momentum,
Q: An object rotates about a fixed axis, and the angular position of a reference line on the object is…
A:
Q: There is a clever kitchen gadget for drying lettuce leaves after you wash them. It consists of a…
A: The angular speed of the Cylinder is, ω= 2.45 revolution/s =15.3938 rad/s The radius of the cylinder…
Q: 3. A telephone pole has been knocked over by the wind so that it makes an angle of 0 with the…
A: Since it contains more than three subparts. Therefore, solution for the first three subparts is…
Q: A circular space station with a radius of 72 m has just been completed. In order to provide…
A:
Q: A turntable with a mass of 12 kg and a radius of 2 meters spins at a constant angular velocity of…
A: M= 12kg , R= 2m , W disk= 140rpm = 14.66 rad/s m= 0.5kg , r= 0.02m , it's center at d=1m away from…
The grand jeté is a classic ballet maneuver in which a dancer executes a horizontal leap while moving her arms and legs up and then down. At the center of the leap, the arms and legs are gracefully extended, as we see in P7.81a. The goal of the leap is to create the illusion of flight. As the dancer moves through the air, he or she is in free fall. But what part of the dancer follows the usual parabolic path? It won’t come as a surprise to learn that it’s the center of gravity. But when you watch a dancer leap through the air, you don’t watch her center of gravity, you watch her head. If the translational motion of her head is horizontal—not parabolic—this creates the illusion that she is flying through the air, held up by unseen forces.
P7.81b illustrates how the dancer creates this illusion. While in the air, she changes the position of her center of gravity relative to her body by moving her arms and legs up, then down. Her center of gravity moves in a parabolic path, but her head moves in a straight line. It’s not flight, but it will appear that way, at least for a moment.
To perform this maneuver, the dancer relies on the fact that the position of her center of gravity
A. Is near the center of the torso.
B. Is determined by the positions of her arms and legs.
C. Moves in a horizontal path.
D. Is outside of her body.
Trending now
This is a popular solution!
Step by step
Solved in 2 steps with 2 images
- A space station shaped like a giant wheel has a radius of 102 m and a moment of inertia of 5.05 x 108 kg. m². A crew of 150 lives on the rim, and the station is rotating so that the crew experiences an apparent acceleration of 1g. When 100 people move to the center of the station for a union meeting, the angular speed changes. What apparent acceleration is experienced by the managers remaining at the rim? Assume that the average mass of each inhabitant is 65.0 kg. m/s² @e When astronauts returnfrom prolonged space flights, they often suffer from bone loss,resulting in brittle bones that may take weeks for their bodies torebuild. One solution may be to expose astronauts to periods ofsubstantial “g forces” in a centrifuge carried aboard their spaceship. To test this approach, NASA conducted a study in which fourpeople spent 22 hours each in a compartment attached to the endof a 28-foot arm that rotated with an angular speed of 10.0 rpm.(a) What centripetal acceleration, in terms of g, did these volunteers experience? (b) What was their linear speed?A spinning globe is slowed at a constant acceleration of 0.750 rad/s2 until it stops. One of the points on the equator moves 23.0° in the first 0.700 s of the slowing phase. (a) Find the total angular displacement of the globe during the acceleration phase. (b) Find the initial angular speed of the globe.
- During a drive by golfer Ai Miyazato, the angular displacement of her club is zero at the top of the backswing and 120 degrees at the bottom of the downswing just before impact with the ball. What is the angular displacement of the golf club in radians?Mary and her younger brother Alex decide to ride the carousel at the State Fair. Mary sits on one of the horses in the outer section at a distance of 2.0 m from the center. Alex decides to play it safe and chooses to sit in the inner section at a distance of 1.5 m from the center. The carousel takes 3.0 s to make each complete revolution. (a) What is Mary's angular speed ?M and tangential speed vM? ?M = rev/s vM = m/s (b) What is Alex's angular speed ?A and tangential speed vA? ?A = rev/s vA = m/sWhile placing a compact disc into a CD player, you notice a small chip on its edge. You attempt to play the CD anyway by placing the CD into the player's deck with the chip at 0o = 12.6° as measured from the +x-axis. The CD begins to rotate with angular acceleration a = 2.31 rad/s². If the CD has been spinning for t = 3.51 s and the disc has a radius of r = 6.00 cm, what are the x-y coordinates of the chip after this time, assuming the center of the disc is located at (0.00,0.00). X = y = cm cm
- A bicycle is turned upside down while its owner repairs a flat tire. A friend spins the other wheel and observes that drops of water fly off tangentially. She measures the heights reached by drops mov- ing vertically (Fig. P7.8). A drop that breaks loose from the tire on one turn rises vertically 54.0 cm above the tangent point. A drop that breaks loose on the next turn Figure P7.8 rises 51.0 cm above the tangent point. The radius of the wheel is 0.381 m. (a) Why does the first drop rise higher than the second drop? (b) Neglecting air friction and using only the observed heights and the radius of the wheel, find the wheel's angular acceleration (assuming it to be constant). Problems 8 and 69.An 8.79cm diameter floppy disk rotates at its fastest at 470 rpm. Part A: Express the angular velocity of the disk in revolutions per seconds? Part B: What is the time period of this revolution? Use scientific notation for your answer. Part C: What is the linear velocity of a point at the rim of the disk? Part D: What is the angular velocity at the center of the disk? Part E: If the disk took 3.2 sec to spin up to 470 rpm from rest, what was the average angular acceleration? How many revolutions did the disk complete within this time? What is the net displacement? Part F: If you turn off the floppy disk drive and the disk comes to a stop in 6.7 s, what is the average angular acceleration for this period of motion?Two bugs, Buzz and Crunchy, are siting on a spinning disk on a horizontal plane. Buzz is sitting halfway and Crunchy is sitting at the outer edge as shown. The radius of the disk is 0.80 m and the disk is rotating with an angular speed of 38 rpm. The coefficient of friction between the bugs and the disk are us = 0.80 and uk = 0.60. What is the magnitude of the friction force on Buzz, in Newtons? Buzz has a mass of 2.0 kg (I know, a big bug!). Your answer needs to have 2 significant figures, including the negative sign in your answer if needed. Do not include the positive sign if the answer is positive. No unit is needed in your answer, it is already given in the question statement. Crunchy
- A 0.50-kg ball that is tied to the end of a 1.7-m light cord is revolved in a horizontal plane, with the cord making a θ = 30° angle with the vertical. An illustration shows a ball suspended from a string. The string forms an angle θ with the vertical as its top end is held stationary in space while the ball moves along a horizontal circular path below. The center of the circular path is shown to be directly below the top end of the string. (a) Determine the ball's speed. m/s(b) If, instead, the ball is revolved so that its speed is 3.8 m/s, what angle does the cord make with the vertical? °(c) If the cord can withstand a maximum tension of 9.6 N, what is the highest speed at which the ball can move? m/sA figure skater has a mass of 65 kg and an angular momentum of 200 kg*m2/s during a camel spin. During this spin, the average radius of gyration changes from 0.33 meters to 0.65 meters in 0.62 seconds. What is the figure skater’s average angular acceleration in degrees/s2 during this 0.62 seconds?An ultracentrifuge accelerates from rest to 9.91 × 10° rpm in 1.75 min. What is its angular acceleration in radians per second squared? angular acceleration: 978 rad/s? What is the tangential acceleration of a point 9.30 cm from the axis of rotation? tangential acceleration: 90.9 m/s? What is the radial acceleration in meters per second squared and in multiples of g of this point at full revolutions per minute? radial acceleration: 1.002 x10° m/s? radial acceleration in multiples of g: