![]() (c) We know that tangential acceleration #a_t# is given by the expression (b) For the seed of mass #m# not to slip the centrifugal force which is equal and opposite to the centripetal force, must be equal or less than force of static friction #f_s#. An insect settles on the edge of the spinning record. Once it gets going around and around, it moves so that the number of revolutions it makes per minute is constant (33 and 1/3). Listen to what comes out of the open end of the paper cone.Consequently, the centripetal (radial) acceleration is In an old record player, the flat round vinyl disc (record) is placed on a turntable which spins around. Gently hold just the top of the cone and let the weight of the cone be supported by the pin, allowing it to move with the motion of the spinning record. When you're ready, slowly lower the pin so that it rests in a groove of the spinning record. Every turntable can play records at 45 and 33 RPM, but only 3-speed record players can support 78. It brakes with constant angular deceleration and stops in 26 seconds. (To get a consistent sound, the pin needs to rest comfortably in the groove as the record rotates beneath it. A 10-inch disc (the oldest of records) rotates at 78 RPM. A turntable rotating at 33 1/3 rpm is shut off. Orient the needle arm so the pin is parallel to the groove and the cone lies tangent to the record. To set up the needle arm, grasp the wider end of the sound cone and bring the pointed end of the cone (with the pin hanging down) close to the record. See if you can spin the record at 33 1/3 revolutions per minute (RPM)-good luck! G ently twirl the pencil, turning the record clockwise. Hi-Fi System Bluetooth Turntable Players with Stereo Bookshelf Speakers, Built-in Phono Preamp, Belt Drive 2-Speed, Adjustable Counterweight, AT-3600L View on Amazon. Make sure the record stays as horizontal as possible. THREE SPEED BELT-DRIVEN TURNTABLE This 3-speed (33 1/3, 45, 78 rpm) record player features UPGRADED PREMIUM SOUND QUALITY with minimum vibrations. To set up the turntable, hold the pencil-and-record assembly on a tabletop, point-side down, like a spinning top (the pencil will act as the axle of your spinning top). This activity requires two people: one to rotate the turntable and one to hold the needle arm and sound cone. ![]() You might see this on an old fashioned record player which could rotate at 33 or 45. ![]() (See photos in the To Do and Notice section to check your assembly.) Another traditional unit for frequency is revolutions per minute or rpm. Use tape if needed to secure the pin in place. About half an inch (1.25 cm) from the tip of the cone, push the pin through both sides of the paper so it sticks out the end at a roughly 45-degree angle.The radius of the driving wheel is r 2.0 cm. The period of the motion is calculated by using the relation between the angular velocity and the time period. The units of the angular velocity are converted by using the conversion factor. The turntable is a uniform disc of mass 1.5 kg and radius R 13 cm, as indicated in the figure. Answer 1 Concept and reason The concepts used are angular velocity, conversion factor, and the time period of the motion. Use tape to keep the paper cone from unraveling. A phonograph turntable driven by an electric motor accelerates at a constant rate (i.e., constant angular acceleration) from 0 to 33.33 revolutions per minute in 2 minutes.Any shape is fine, but make sure one end of the cone (the tip) is closed. Starting in one corner, roll the piece of paper diagonally to form a cone shape. 1 Answer Jane A turntable rotates at 45r.p.m means, it takes 1m to complete 45 rotations, So,time taken to complete 1 rotation is 1 45 60s 1.34s This is the time period ( T) (by definition) So,angular speed 2 T 2 1.34 4.If not, apply more tape as needed to ensure that the record and pencil do not move independently. Test your assembly by twirling the pencil. A record is 30 cm in diameter and revolves at 33 1/3 rpm (revolutions per minute).Wrap tape around the pencil just below the record, to ensure the pencil stays in place and can't slide back through the center hole.A ngle the pencil so it is perpendicular to the record, then position the assembly so the record lies horizontal and the pencil shaft is vertical, with the tip of the pencil pointing down towards the table and the eraser end pointing up towards the ceiling. The speed of a point on the edge of the record is: a. the records sound, the fine tuning that the turntables rotation speed requires. Slide the pencil through the center hole of the record so the tip extends an inch or so (a few cm) beyond the other side. A vinyl record turns at 33.3 revolutions per minute and has a radius of 15.0 cm. Its easy to forget to switch the speed selector from 33 rpm to 45 rpm.
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