Question

Mark notices he has dropped calls on his cell phone when he walks into his bedroom. His friend told him to try and wrap aluminum foil around his phone to get a better signal. Mark talks on the phone 3 times while walking into his bedroom and drops 2 of the 3 calls. He wraps his phone in aluminum foil and talks on the phone 3 more times while walking into his bedroom. With the aluminum foil on his phone, he only drops 1 phone call.

A. Independent Variable=
B. Dependent Variable=
C. Control=

Answer 1

The independent variable is the aluminum foil; the dependent variable is the number of dropped calls; the control can be the bedroom environment. To find the mass of a piece of foil, calculate its volume and multiply it by aluminum's density. The density of aluminum suggests a wad of foil should sink, but it may not due to air pockets and water surface tension.

Step-by-step explanation:

The student's question involves an experiment with a potential influence on cell phone signal strength. The independent variable in this scenario is the use of aluminum foil around the phone, as it is what is being changed or manipulated during the experiment. The dependent variable is the number of dropped calls, which depends on the condition of the independent variable - whether the phone is wrapped in aluminum or not. The control in the experiment could be the bedroom environment where the calls are made, as it should remain consistent throughout the test to ensure accurate results.

Making Connections: Take-Home Investigation

1. To determine the mass of aluminum foil that measures 10 cm by 15 cm with a thickness of 0.016 mm, one would need to know the density of aluminum. Once the volume is calculated (area multiplied by thickness), it can be multiplied by the density of aluminum to find the mass.
2. When considering the optimal boat shape for holding the most cargo, it likely involves maximizing the amount of displaced water while keeping the surface area of the foil larger than the water's surface tension threshold to prevent sinking.

The density of aluminum foil is 2.7 times that of water, which would suggest that the foil should sink if shaped in a way that does not allow it to displace a greater volume of water than its own mass. When rolled up into a ball, it might not sink immediately due to air trapped within the foil or the surface tension of water. However, with manipulation to remove trapped air and disrupt surface tension, the aluminum foil could indeed sink.