Two resistanceless rails rest 24 cm apart on a 4.0 ∘ ramp. They are joined at the bottom by a 0.70 Ω resistor. At the top a copper bar of mass 0.080 kg (ignore its resistance) is laid across the rails. The whole apparatus is immersed in a vertical 0.50 T field. Part A What is the terminal (steady) velocity of the bar as it slides frictionlessly down the rails

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?

An insurance company wants to know if the average speed at which men drive cars is higher than that of women drivers. the company took a random sample of 27 cars driven by men on a highway and found the mean speed to be 72 miles per hour with a standard deviation of 2.2 miles per hour. another sample of 18 cars driven by women on the same highway gave a mean speed of 68 miles per hour with a standard deviation of 2.5 miles per hour. assume that the speeds at which all men and all women drive cars on this highway are both approximately normally distributed with unknown and unequal population standard deviations.

What is the force that opposes motion and works against the downward pull? a) friction b) gravity c) weight d) acceleration