I'm also stumped by this one:

3. A bimetallic strip (117 cm by 1 cm by 0.01cm) has aluminum (a = 23x10^-6 1/Celsius) on one side and has steel (a= 12x10^-6 1/Celsius) on the other. It is perfectly straight at room temperature (20 celsius). What change in temperature is required to change the strip into a full circle? (assume change in thickness is negligible)

"a" is the coefficient of linear thermal expansion and can be defined as the fractional change in length of a specific substance that has undergone a change in temp. of 1 degree Celsius.

Again, any starting points are appreciated!

To determine the change in temperature required to change the strip into a full circle, we need to understand the concept of thermal expansion and apply it to this particular scenario.

Thermal expansion refers to the tendency of an object to expand or contract in response to changes in temperature. The change in length of an object due to temperature change can be determined by multiplying the original length by the coefficient of linear thermal expansion (α) and the change in temperature.

In this case, we have a bimetallic strip consisting of aluminum and steel. Each metal will undergo its own expansion based on its coefficient of linear thermal expansion. The strip will curve or bend, and our objective is to determine the temperature change that will result in a full circle.

To approach this problem, we need to consider the bending of the strip. When the strip becomes a full circle, the outer side will expand more than the inner side. This difference in expansion causes the curvature. Therefore, we need to find the temperature change at which the outer side expands enough to form a full circle while the inner side remains unchanged.

Here are the steps to solve this problem:

1. Calculate the change in length for each metal:
- For aluminum: ΔL_aluminum = L_aluminum * α_aluminum * ΔT
- For steel: ΔL_steel = L_steel * α_steel * ΔT

2. Since the change in length must be equal for both metals at the point of forming a full circle, we can equate the two expressions:
ΔL_aluminum = ΔL_steel

3. Since we're only interested in the change in temperature, set up the equation:
L_aluminum * α_aluminum * ΔT = L_steel * α_steel * ΔT

4. Rearrange the equation to solve for ΔT:
ΔT = (L_steel * α_steel) / (L_aluminum * α_aluminum)

5. Substitute the given values for L_aluminum, L_steel, α_aluminum, and α_steel into the equation above.

6. Calculate ΔT to determine the change in temperature required to change the strip into a full circle.

By following these steps, you should be able to find the answer to the question.