Two pennies are taking a circular ride on the record at right. Penny B is halfway to the outside. Penny A is on the outside.
In the example above, which type of force provides the centripetal force
a.) FN b.) Fg c.) Ft d) FF
e.) there is no centripetal force ab.) none of the above

What would the difference of spectral lines emitted by hydrogen gas in distant galaxies which is normally found at a wavelength of 21 cm on earth, be observed at 21.1 centimeters?

Imagine you had to physically add electrons, one at a time, to a previously neutral conductor. you add one electron very easily, but the second electron requires more work. in your initial post to the discussion, explain why this is. also, what happens to the work needed to add the third, fourth, fifth, and subsequent electrons

Arrange the images in order to show how lake-effect snow occurs.