A scientist is performing an experiment and wants it to run on a combined photovoltaic and solar thermal system. The sunlight around his laboratory provides an average power density of 300 W/m2 for 6 hours each day. His experiment demands energy for a heater to convert 1500L of water to steam at 150℃ every day. The initial temperature of the water is 20℃. How many solar panels will he need to buy?

If the force on an object is in the negative direction, the work it does on the object must be [2 points a) negative. b) positive c) the work could be either positive or negative, depending on the direction the object moves

Which of the following is the phase that results when the moon is on the opposite side of the earth from the sun? a. quarter moon b. crescent moon c. new moon d. full moon

A5 foot by 5 foot box culvert is buried 6 feet beneath the surface of the ground. a crosssection of this very long culvert (into and out of the page) is illustrated below. assume that the soil in which the culvert is buried has the following properties: jt = 120 pcf, w = 12%, ko = 0.50, ka = 0.33, and kp = 3.00. calculate the total horizontal force per unit length of culvert (fh) felt on one of the vertical faces of the culvert.