7. The English Channel is 35 km wide at its narrowest point, which is where most swimmers attempt to cross north to south from England to France. The current across this portion of the English Channel runs at about 2
km/h east to west.
a. If a swimmer has a relative velocity to the shore of 3 km/h north to south, how long will it take her to
cross the 35 km distance?

Hydrogen atoms are excited by a laser to the =4n=4 state and then allowed to emit. what is the maximum number of distinct emission spectral lines (lines of different wavelengths) that can be observed from this system? 8 6 2 7 4 5 1 3 calculate the wavelength of the 4⟶14⟶1 transition. =λ=

Abowling ball rolling down the lane toward the pins has gravitational potential energy. a. no b. a lot of c. a little

22. the top of a cliff is located a distance h above the ground. at a distance h/2 there is a branch that juts out from the side of the cliff, and on this branch a bird's nest is located. two children throw stones at the nest with the same initial speed, one stone straight downward from the top of the cliff and the other stone straight upward from the ground. in the absence of air resistance, which stone hits the nest in the least amount of time?