19) A typical compact disk has a mass of 15 grams and a diameter of 120 mm. What is its moment of inertia about an axis through its center, perpendicular to the disk? (5 points) 20) You're carrying a 3.6-m-long, 25 kg pole to a construction site when you decide to stop for a rest. You place one end of the pole on a fence post and hold the other end of the pole 35 cm from its tip. How much force must you exert to keep the pole motionless in a horizontal position? (5 points) Hint: 50m 21)) A vendor hangs an 8.0 kg sign in front of his shop with a cable held away from the building by a lightweight pole. The pole is free to pivot about the end where it touches the wall, as shown in Figure. What is the tension in the cable? (5 points) Cable LITTLE SHOP OF PHYSICS