# Torque and rotational inertia

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##### Intros

##### Examples

###### Lessons

- A person exerts a force of 45N on the handle of a door 65cm wide.
- Calculate the net torque about the axle of the of the wheel shown below. Assume that a friction torque of 0.60 $N.m$ opposes the motion.
- A torque of 66 $N.m$ is required to tighten the bolts on the cylinder head of a car engine. The wrench used to tighten the bolt is 26cm long.
- Two small weights of mass 4.0kg and 6.0kg are mounted 6.0m apart on a light rod as shown below. Calculate the moment of inertia of the system;
- A 12.0N force is applied to a cord wrapped around a pulley of mass $M$ = 6.00kg and radius $R$= 22.0cm. The pulley accelerates uniformly from rest to an angular speed of 40.0 rad/s in 2.00s. If there is a frictional torques $\tau _{fr}$ = 1.20$m.N$ at the axle, determine the moment of inertia of the pulley as it rotates around its center.
- Determine the moment of inertia for the following uniform objects:
- An Atwood's machine consists of two masses, $m_{1}$ = 4.0kg and $m_{2}$ = 7.0kg, which are connected by a massless inelastic cord that passes over a pulley. The pulley has radius $R$ = 0.4m and moment of inertia $I$ =4.0 kg. $m_{2}$
about its axle.