(a) What is its angular speed in radians per second What is the linear speed of a point on the record (b) 15 cm and (c) 7. (e) Compare the kinetic energy changes in parts (b) through (d). A vinyl record on a turntable rotates at 33 1/3 rev/min. (d) Determine the change of kinetic energy of the system consisting of student alone without the dumbbells. (a) Assuming the angular acceleration is constant, what is its. Determine the magnitude of the resistive torque that slows the A turntable reaches an angular speed of 33.3 rpm in 2.0 s starting from rest. The turntables rotational inertia is 1.0 x 10 -2 kg m2. (c) Determine the change in the kinetic energy of the system consisting of the two dumb bells alone without the student. A turntable turning at rotational speed 39 rpm stops in 30 s when turned off. Most turntables can play 33s and 45s, while 78s require a certain kind. (b) Determine the change of kinetic energy of the system consisting of the student together with the two dumbbells. 33, 45, and 78 RPM represents the speed at which the record spins on your turntable. A quick recalibration of a turntables playing speed can often solve things, and will help to figure out how far off hitting the perfect 33 1/3 rpm or 45 rpm. (a) Determine the student’s final rotational speed.
The marks are most commonly dots, lines or wedges.A student sitting on a chair on a circular platform of negligible mass rotates freely on an air table at initial rotational speed 2.0 r a d / s 2.0 \mathrm 5.0 kg ⋅ m 2.
#A TURNTABLE AT ROTATIONAL SPEED 33 RPM FULL#
There should be 54 marks for “60Hz” making a full circle of 216. There should be 45 marks for “50Hz” making a full circle of 180. Locate the 33⅓ RPM markings: it’s likely to be the ring with the mostĬount the number around a quarter of the circle. These are very fine and need to be printed near the edge of a 12 inch disc to be able to view them properly. There are also strobe discs that have 300Hz markings. This shows that it is better to use 120Hz markings and “60Hz” light if 45RPM is important to you. So for 33 1/3 RPM the number of marks for 100Hz and 120Hz are:ġ00 / 45 * 60 = 133.33 (oops)–rounding down to 133 gives a speed of 45.11RPM The number of marks therefore corresponds to the following rule:įrequency / RPM * 60 (second in a minute) = number of marks Interestingly, the new generation of compact fluorescent lamps flash at an unrelated rate so are useless for strobe illumination. The reason for the doubling is that a mains lamp "flashes" at twice the mains frequency rate (once per half cycle). Calculate the moment of inertia of a 12.2-kg sphere of radius 0.623 m when the axis of rotation is through its center. What was its angular acceleration w (33 Revolutions/Minute)(2 p. Most platter and disc markings were originally designed for use with AC mains lamps, so they correspond to the frequencies above. A phonograph turntable reaches its speed of 33 rpm after making 1.7 revolutions. The turntable's rotational inertia is 1.0 X 10-2 kg - m2. Determine the mgnitude of the resistive torque that slows the turntable. The turntable's rotational inertia is 1.3×102kgm2. Question: A turntable turning at rotational speed 33 rpm stops in 50 s when turned off. Slight speed inaccuracy shows as a gradual drift in the markings. A turntable turning at rotational speed 33 rpm stops in 50 s when turned off. This problem has been solved You'll get a detailed solution from a subject matter expert that helps you learn core concepts. When the speed is accurate, the motion of the marks is "frozen" by the strobe light.
A flash illuminates each individual line as it passes. A turntable apparatus driven directly by an electronically commutated motor having a speed of 33 rpm or 45 rpm which decreases the rumble and the wow and. and (b) the number of revolutions it makes before coming to rest. Calculate (a) the magnitude of its angular acceleration. The platter or disc is marked with dots or lines. (4ed) 10.1 The turntable of a record player rotates at a rate of 33 1 / 3 rev/min (rpm) and takes 60.0 s to come to rest when switched off. Most commonly at 100 (50Hz version) or 120 times a second (60Hz version).
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