40 degrees north runs along 146th street on the north side of Indianapolis. What is the rotational velocity of the surface of the earth at 40 degrees north?

Answer 1

the Earth completes one revolution in 24 hr

so, how long is the 40th parallel?

the "rotational" radius is equal to the radius of the Earth times cos(40º)

the length of the parallel (circumference) is 2π times the radius

divide the circumference by 24 hr to get the rotational velocity