An aluminum rod 0.500 m in length and with a cross sectional area of 2.50 cm2 is inserted into a thermally insulated vessel containing liquid helium at 4.20 k. the rod is initially at 300 k. (a) if one half of the rod is inserted into the helium, how many liters of helium boil off by the time the inserted half cools to 4.20 k? (assume the upper half does not yet cool.) (b) if the upper end of the rod is ma

The boat's velocity relative to the riverbank can be resolved into two components. the component going north is 2.7 m/s and the component going west is 1.2 m/s.we add these two vectors and then find the magnitude of the resultant to get the speed.the magnitude of the resultant vector from adding can be obtained by the pythagorean theorem.    to two significant figures, the boat's speed relative to the riverbank is 3.0 m/s.

It is increased due to the doppler effect. (apex)

Not sure but i think it's b.