A. situation a: a 20-kg block is pressed against a relaxed spring on a frictionless surface. the spring is compressed by ∆x = 10 cm from its equilibrium position x = x 0 e . the block is released and the spring uncompresses. the speed of the block at x = x 0 e is va, f = 5.0 m/s.
b. situation b: the same 20-kg block is pressed against two relaxed springs that are attached in series on a frictionless surface. (these two springs are both identical to the spring in situation a). the entire spring assembly is compressed by ∆x = 10 cm from its equilibrium position x = x 0 e . the block is released and the spring assembly uncompresses. the speed of the block at x = x 0 e is vb, f question:
what is the value of vb, f ?
(a) 3.5 m/s
(b) 2.5 m/s/s
(c) 5.0 m/s
(d) 6.4 m/s
(e) 7.0 m/s.

Suppose water is leaking from a tank through a circular hole of area ah at its bottom. when water leaks through a hole, friction and contraction of the stream near the hole reduce the volume of water leaving the tank per second to cah 2gh , where c (0 < c < 1) is an empirical constant. a tank in the form of a right-circular cone standing on end, vertex down, is leaking water through a circular hole in its bottom. (assume the removed apex of the cone is of negligible height and volume.) (a) suppose the tank is 20 feet high and has radius 8 feet and the circular hole has radius 2 inches. the differential equation governing the height h in feet of water leaking from a tank after t seconds is dh dt = − 5 6h3/2 . if the height of the water is initially 8 feet, how long will it take the tank to empty? (round your answer to two decimal places.)

An element becomes a positively charged ion when itloses protons. loses electrons. gains electrons. gains neutrons.

When a lead acid car battery is recharged by the alternator, it acts essentially as an electrolytic cell in which solid lead(ii) sulfate is reduced to lead at the cathode and oxidized to solid lead(ii) oxide at the anode. suppose a current of is fed into a car battery for seconds. calculate the mass of lead deposited on the cathode of the battery.