Question
A long playing record revolves with a speed of 
and has a radius of 15 cm. Two coins are placed at 4 cm and 14 cm away from the centre of the record. If the coefficient of friction between the coins and the record is 0.15, which of the two coins will revolve with the record?
Solution
The coin will revolve along the record, if the centrifugal force on the coin is less or equal to the force of limiting friction.
If it is not so, the coin will slip.
i.e. the coin will revolve along with record only if,
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Given here,
∴![<pre>uncaught exception: <b>mkdir(): Permission denied (errno: 2) in /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php at line #56mkdir(): Permission denied</b><br /><br />in file: /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php line 56<br />#0 [internal function]: _hx_error_handler(2, 'mkdir(): Permis...', '/home/config_ad...', 56, Array)
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= 0.1206m
= 12.06 cm
Therefore, the coin at a distance 4 cm will revolve along the record.
If it is not so, the coin will slip.
i.e. the coin will revolve along with record only if,
Given here,
∴
= 0.1206m
= 12.06 cm
Therefore, the coin at a distance 4 cm will revolve along the record.
