Some smartphones run on lithium-ion batteries, which can stop functioning when the phone's temperature is too far outside a certain range. For one particular type of smartphone, the optimal range is between 0°C to 35°C.
A designer made several phone cases that help to minimize thermal energy transfer out of the phone so that it can withstand low temperatures. She tested her
designs by placing the phone and case in a container kept at 0°C, then monitored the phone's internal temperature over time. Her test results are shown below.
Temperature (°C)
Time (min) Leather Sleeve Foam Sheet Double-walled Metal Thick Plastic
0
35.4
352
35.3
35.2
30
21.0
27.7
18.9
14.5
60
18.6
23.0
10.2
8.8
How could the phone case be modified to improve the design?
OA
Make the walls of the metal case thicker,
ОВ.
Decrease the thickness of the plastic.
OC.
Put the case designs on a different type of phone.
OD
Combine the leather and the foam into layers.