When a piece of wood is distorted by a karate chop, the top of the board is compressed while the bottom is stretched as shown. Therefore, you must first

consider the change in length of the bottom of the board where the break

begins. Chantal is a black belt in karate and she breaks a 30.0-cm piece of

wood with a force of 70.0 N, changing it in length by 4.0 104 cm. What is

the cross-sectional area of the piece of wood? (Ywood 1.0 109 N/m2)

Na food processing facility, a spherical container of inner radius r1 5 40 cm, outer radius r2 5 41 cm, and ther- mal conductivity k 5 1.5 w/m · k is used to store hot water and to keep it at 100°c at all times. to accomplish this, the outer surface of the container is wrapped with a 800-w electric strip heater and then insulated. the temperature of the inner surface of the container is observed to be nearly 120°c at all times. as- suming 10 percent of the heat generated in the heater is lost through the insulation, (a) express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the container, (b) obtain a relation for the variation of temperature in the container material by solving the differential equation, and (c) evaluate the outer surface tempera- ture of the container. also determine how much water at 100°c this tank can supply steadily if the cold water enters at 20°c.

Free runners jump long distances and land on the ground or a wall. how do they apply newton’s second law to lessen the force of impact?

The magnetic field inside a superconducting solenoid is 4.50 t. the solenoid has an inner diameter of 6.20 cm and a length of 26.0 cm. determine (a) the magnetic energy density in the field and (b) the energy stored in the magnetic field within the solenoid.