A 0004kg bullet traveling horizontally whth a speed of 100

A 0.004-kg bullet traveling horizontally whth a speed of 1.00 * 10^3 ms enters an 16.0-kg door, embedding itself 10.0 cm from the side opposite the hinges. The 1.00-m-wide door is iree to swing on its hinges. a)At what angular speed does the door swing open immediately after the collision? b)Calculate the change of the kinetic energy of the door-bulkt system during the collision. A 30.0-kh child sits on one end of a long uniform beam having a mass of 20.0kh, and a 50.0-kg child sits on the other end. the beam balances when a fulcurm is placed below the beam a distance 1.0m from the 30.0-kh chid. How long is the beam?

Solution

3) When the beam is balanced, there is no net torque around any point, including the fulcrum

The distance from the center of the beam to the fulcrum is d = L/2 - 1.0 m

sigma T = 0 = (30 * 1.0 m * g) - (20* g * ( L/2 - 1.0 ) ) - (50 * ( L - 1.0 ))

30 = 10 L - 20 + 50 L - 50

100 = 60 L

L = 1.67 m