Posted by Mare on Wednesday, November 18, 2009 at 11:07pm.
A merry go round in the park has a radius of 1.8 m and a rotational inertia of 900 kgm^2. A child pushes the merry go round with a constant force of 80 N applied at the edge and parrallel to the edge. A frictional torque of 12 Nm acts at the axle of the merry go round. What is the rotational acceleration of the merry go round if the child stops pushing after 15 seconds? How long will it take for the merry go round to stop turning?

physics  drwls, Thursday, November 19, 2009 at 12:49am
After the child stops pushing, the rotational acceleration is negative. it slows down.
Use the equation
alpha = L/I
where alpha is the angular DEceleration, I is the moment of inertia and L is the frictional torque.
To determine how long it takes to stop. you need to calculate how fast it is going when the pushing force stops. That is a somewhat harder problem, but uses the same equation. You need to calculate the angular acceleration rate while it is being pushed, and multiply that by the time (15 seconds).
Use the same L/I equation, but in this accvelerating case, the torque is the difference of the pushing and frictional torques.
Answer This Question
Related Questions
 Physics  A merrygoround in the park has a radius of 1.8 m and a rotational ...
 physics  A merrygoround in the park has a radius of 1.8 m and a rotational ...
 Physics  A merrygoround with r = 4m and a perfect frictionless bearing is ...
 Physics Inertia : Merrygoround  A playground merrygoround of radius 1.96 m ...
 physics  A merrygoround in a playground has a mass of 200 kg and radius of 1....
 physics  A playground merrygoround has a radius 2.6 m and a rotational ...
 Physics  A 21kg child starts at the center of a playground merrygoround that...
 physics  A playground merrygoround of radius 2.00 m has a moment of inertia I...
 physics  A child of mass 54.7 kg sits on the edge of a merrygoround with ...
 Physics: merrygoround question  A playground merrygoround of radius 1.92 m ...
More Related Questions