The "U" is part of the motto, "In God We Trust" which arcs along the top of the coin.
If the coin is a US Kennedy half dollar dated 1974 it has no silver in it and is face value.
Yes, it is 40% silver however and not 90% silver like half dollars dated 1964 and earlier.
Absolutely. Dimes, quarters, and half dollars dated 1964 and earlier, and dollars dated 1935 and earlier, are 90% silver and 10% copper.
A US Kennedy half dollar dated 1969 is only 40% silver with a value of about $2.00.
With a date of 1979 the coin has no silver in it. 1969 was the last 40% silver circulating US half dollar. The coin is worth 50 cents.
No Kennedy half dollars dated 1982 are silver, those are 50 cents. But if you mean a 1982 George Washington commemorative half dollar, this coin is about $14.00.
The U.S. didn't make any half dollars dated 1804.
U.S. half dollars dated before 1965 weigh 12.5 grams and contain 90% silver.
This coin is 40% silver. Too bad it is not from 64 or earlier, as those were 90% silver. It is worth a dollar or two.
Value depends on if it's a Walking Liberty half dollar or a Monroe Doctrine half dollar, both are dated 1923 and both have "S" mintmarks.
90% silver half dollars were minted until 1965, all half dollars dated 1964 and before are 90% silver. From 1965-1970 the half dollar was 40% silver. From 1971-present circulation issue half dollars are copper-nickel and contain no silver.
None of the coins listed in this question contain any silver or gold. All are just face value.