Your friend in physics class that if the rock suddenly were to fall off the tabl

Question

Your friend in physics class that if the rock suddenly were to fall off the table, the turntable would speed back up to 10 rotations per minute. His logic goes like this: the turntable's moment of inertia would return to able would speed back up rock was dropped on it, and because the rock-table system is isolated, with its original value (that is, before the rock was dropped on it), and because the moment of inertia has dropped, no outside net force acting on it, angular momentum the would have to be conserved, So because the moment of inertia has dropped, the angular velocity of the table must increase. Thoroughly critique your friends reasoning. List at least one thing they get correct and one thing they are wrong about In the course of your answer, explain what will actually happen to the turntable's speed and why

Explanation / Answer

The thing they got correct is that angular momentum is conserved if net force is zero on the system

Wrong part is that table will rotate at speed of 10 rev/min. When rock is just falling, speed is zero so angular momentum is still zero so table will not rotate.If rock is allowed to fall at speed and with some angle to radius vector ( not along radius vector) then table will rotate as it will have some angular momentum and to balance that table will rotate to make angular momentum zero again

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.