Select all of the true statements. π is the area of a circle of radius 1
π is the area of a circle of diameter 1
π is the circumference of a circle of radius 1
π is the circumference of a circle of diameter 1
π is the constant of proportionality relating the diameter of a circle to its circumference
π is the constant of proportionality relating the radius of a circle to its area

It is may 5 and you are somewhere in the northern hemisphere. if you determine that the noon sun is 51 degrees above your southern horizon, what is the latitude of your location

An engineer designs a roller coaster so that a car travels horizontally for 152 ft, then climbs 137 ft at an angle of 34.0° above the horizontal. it then moves 137 ft at an angle of 48.0° below the horizontal. if we take the initial horizontal motion of the car to be along the +x-axis, what is the car's displacement? (give the magnitude of your answer, in ft, to at least four significant figures and give the direction of your answer in degrees counterclockwise from the +x-axis.)

Consider a 1000 w iron whose base plate is made of 0.5 cm thick aluminum alloy 2024-t6 (ρ = 2770 kg/m3 and cp = 875 j/kg°c). the base plate has a surface area of 0.03 m2. initially, the iron is in thermal equilibrium with the ambient air at 22°c. assuming 90% of the heat generated in the resistance wires is transferred to the plate, determine the minimum time needed for the plate temperature to reach 200°c.