Constants light of wavelength 640 nm falls on two slits and produces an interference pattern in which the third-order bright red fringe is 46 mm from the central fringe on a screen 2.6 m away. what is the separation of the two slits?
express your answer to two significant figures and include the appropriate units.

Astone is dropped from the upper observation deck of a tower, 250 m above the ground. (assume g = 9.8 m/s2.) (a) find the distance (in meters) of the stone above ground level at time t. h(t) = (b) how long does it take the stone to reach the ground? (round your answer to two decimal places.) s (c) with what velocity does it strike the ground? (round your answer to one decimal place.) m/s (d) if the stone is thrown downward with a speed of 2 m/s, how long does it take to reach the ground? (round your answer to two decimal places.) s