Questions 25 through 27 concern a classic figure-skating jump called the axel. A skater starts the jump moving forward as shown in Figure Q7.25, leaps into the air, and turns one-and-a-half revolutions before landing. The typical skater is in the air for about 0.5 s, and the skater's hands are located about 0.8 m from the rotation axis. Figure Q7.25 26. The skater’s arms are fully extended during the jump. What is the approximate centripetal acceleration of the skater’s hand? A. 10 m/s 2 B. 30 m/s 2 C. 300 m/s 2 D. 450 m/s 2
Questions 25 through 27 concern a classic figure-skating jump called the axel. A skater starts the jump moving forward as shown in Figure Q7.25, leaps into the air, and turns one-and-a-half revolutions before landing. The typical skater is in the air for about 0.5 s, and the skater's hands are located about 0.8 m from the rotation axis. Figure Q7.25 26. The skater’s arms are fully extended during the jump. What is the approximate centripetal acceleration of the skater’s hand? A. 10 m/s 2 B. 30 m/s 2 C. 300 m/s 2 D. 450 m/s 2
Questions 25 through 27 concern a classic figure-skating jump called the axel. A skater starts the jump moving forward as shown in Figure Q7.25, leaps into the air, and turns one-and-a-half revolutions before landing. The typical skater is in the air for about 0.5 s, and the skater's hands are located about 0.8 m from the rotation axis.
Figure Q7.25
26. The skater’s arms are fully extended during the jump. What is the approximate centripetal acceleration of the skater’s hand?
A disk rotates freely on a vertical axis with an angular velocity of 30 rpm. An identical disk rotates above it in the same direction about the same axis, but without touching the lower disk, at 20 rpm. The upper disk then drops onto the lower disk. After a short time, because of friction, they rotate together. The final angular velocity of the disks isA. 50 rpmB. 40 rpmC. 25 rpmD. 20 rpmE. 10 rpm
A “blink of an eye” is a time interval of about 150 ms for an average adult. The “closure” portion of the blink takes only about 55 ms. Let us model the closure of the upper eyelid as uniform angular acceleration through an angular displacement of 15.4°.
a. What is the value of the angular acceleration the eyelid undergoes while closing? answer in rad/s^2
b. What is the tangential acceleration of the edge of the eyelid while closing if the radius of the eyeball is 1.25 cm? answerin m/s^2
An ultracentrifuge accelerates from rest to 108600rpm in 2.1min.
A. What is its angular acceleration in units of radians per second squared?
B. What is the tangential acceleration, in meters per second squared, of a point 9.5cm from the axis of rotation?
C. What is the centripetal acceleration, in multiples of g, of this point at full speed?
Chapter 7 Solutions
College Physics: A Strategic Approach (3rd Edition)
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