What key observations forced scientists to change their views about the location of the Sun within the Milky Way?

Sara is creating an experiment. her hypothesis states the following. if i increase the air in my tires, then i will get better gas mileage. if this is her hypothesis what column titles do we need in our date table? a. air pressure in tire (psi) and gas mileage (mph) b. air pressure in the atmosphere (psi) and gas mileage (mph) c. miles (m) and gallons per mile (g) d. old battery and new battery

Keneila is attempting to ski down a 20 m high friction free hill for the first time. she has a speed 10 m/s at the top. what is her kinetic energy when she is a the bottom, 20 m ? (a)2500 j (b)9800 j (c)12300 j (d)3100j (e)15000j

Uranium has two naturally occurring isotopes. 238u has a natural abundance of 99.3% and 235u has an abundance of 0.7%. it is the rarer 235u that is needed for nuclear reactors. the isotopes are separated by forming uranium hexafluoride uf6, which is a gas, then allowing it to diffuse through a series of porous membranes. 235uf6 has a slightly larger rms speed than 238uf6 and diffuses slightly faster. many repetitions of this procedure gradually separate the two isotopes. what is the ratio of the rms speed of 235uf6 to that of 238uf6? express your answer to five significant figures.