Iplace a 500-g ice cube (initially at 0°c) in a styrofoam box with wall thickness 1.0 cm and total surface area 600 cm2 .

if the air surrounding the box is at 20°c and after 4 hours the ice is completely melted, what is the conductivity of the styrofoam material? (lf = 80 cal/g)
a. 9.6 × 10−5cal/s⋅cm⋅°c
b. 2.8 × 10−6cal/s⋅cm⋅°c
c. 1.15 × 10−2cal/s⋅cm⋅°c
d. 2.3 × 10−4cal/s⋅cm⋅°c

What effects result when there is an impact between earth and an asteroid? check all that apply. a. massive flooding. b. extinction of many life forms. c.major earthquakes change in average global temperature. d. giant dust cloud

Select light for the type of wave, adjust the wavelength so that the light is red, and increase the amplitude of the light to the max. then, select the start button at the source location to begin producing the waves. light is a form of electromagnetic wave, containing oscillating electric and magnetic fields. the wave amplitude detector mentioned above shows how the electric field oscillates in time at the location of the probe. the amplitude of the wave at the location of the probe is equal to the maximum electric field measured. how does the amplitude of the wave depend on the distance from the source?

Aspring has a relaxed length of 33 cm (0.33 m) and its spring stiffness is 6 n/m. you glue a 76 gram block (0.076 kg) to the top of the spring, and push the block down, compressing the spring so its total length is 15 cm. you make sure the block is at rest, then at time t=0 you quickly move your hand away. the block begins to move upward, because the upward force on the block by the spring is greater than the downward force on the block by the earth. calculate y vs. time for the block during a 0.09-second interval after you release the block, by applying the momentum principle in three steps each of 0.03-second duration.