This is usually lab time but today it will be recitation.

Announcements #

Spine problem

To find these unknowns we use the sum of the torques

Fill out distances

Find perpendicular components

Solve for $F_m$

Back muscle exerts 2.3 times your weight to hold you up!

Total force

Just bending over the force you put on your spine is 2.5 times your body weight.

Kinematics problem

Final angular velocity will be 0

What does the sign of the answer mean?

Means it is slowing down.

Rotational inertia will be given to us. Not expected to calculate or memorize them.

Point particle

Ring

Disc / clinder

Solid sphere

Atwood machine (w/ pulley)

What is the acceleration of the masses?

Frictionless pulley

Free body of $m$

Free body of $2m$

The rope is not stretching

Free body of pulley

Sum the torques

Pivots on the axel

The tensions causes the rotation. Clockwise positive

3 equations with a new unknown

Solve for $T_1$ and $T_2$

HW Problems #

4 #

Problem is looking for force the ground exerts on the hoof $F_{GY}$

Divide total mass by 2 because only looking at one hoof.

Unknowns

Choose pivot point at hoof

Find angles

CCW positive torques

Correction: actually force of wall divided by two because its being supported by both hoofs.