Which of the following statatements is correct?
a. Thermos bottles keep food warm by combating heat loss through convection.
b. A thick quilt is an example of an isulator with a low R value
c. An object that is cool to the touch at room temperature is a poor conductor of heat
d. Wearing a white shirt on a hot, sunny day keeps you cool because it emits more solar energy than a darker shirt
e. All of th above statements a-d are all correct
f. None of the above statements a-d are all incorrect
To determine which statement is correct, let's analyze each statement separately:
a. Thermos bottles keep food warm by combating heat loss through convection.
To understand if this statement is correct, we need to know how thermos bottles work. Thermos bottles have a double-walled design with a vacuum in-between. This vacuum helps in reducing heat transfer through convection, conduction, and radiation. So, statement a is correct.
b. A thick quilt is an example of an insulator with a low R value.
To determine if this statement is correct, we need to understand what R-value represents. R-value is a measure of the thermal resistance of a material. Higher R-values indicate better insulation properties. So, if a thick quilt has a low R-value, it means it has poor insulation properties. Therefore, statement b is incorrect.
c. An object that is cool to the touch at room temperature is a poor conductor of heat.
To verify this statement, we need to consider if being cool to the touch indicates a poor conductor of heat. Generally, materials that conduct heat efficiently feel warm or hot to the touch because they easily transfer heat to our skin. Therefore, an object that feels cool to the touch at room temperature is likely a good insulator and a poor conductor of heat. Thus, statement c is correct.
d. Wearing a white shirt on a hot, sunny day keeps you cool because it emits more solar energy than a darker shirt.
To determine the accuracy of this statement, we need to consider the properties of different colored fabrics. Dark-colored fabrics absorb more solar energy, while light-colored fabrics reflect it. When it comes to keeping cool on a hot, sunny day, wearing a white shirt that reflects most of the solar energy can help reduce heat absorption compared to a darker shirt that absorbs more heat. So, statement d is correct.
Based on our analysis, statements a, c, and d are correct, while statement b is incorrect. Therefore, the correct option is e.