You have to know the coin's date:
1964: On the reverse, to the left of the stem of the olive branch. D = Denver, blank = Philadelphia
1965-67: No mint marks were used due to the coin shortage
1968-1979: Above the date on the front. D = Denver, blank = Philadelphia; proof coins have an S.
1980-present: same as 1968-79, except P = Philadelphia.
It doesn't look like anything, because there's no such thing. Kennedy wasn't featured on the half dollar until 1964. In 1950, Kennedy was still a Congressman, and Benjamin Franklin was on the half.
a half dollar looks like a dollar cut in half
Please take another look at the coin. That's President John F. Kennedy on the half dollar. There's more information at the Related Question.
The heads side looks like all other Kennedy half dollars, but with the dates 1776-1976. The on the back, instead of an eagle, it's Independence Hall.
Please turn the coin over and look at the denomination on the back. It's a HALF dollar.
Sorry, no such coin as a "Kennedy silver dollar", JFK only appears on the Half dollars from 1964 to date. Look at the coin again and post new question.
Please, turn the coin over and look at the denomination on the back. It's a HALF dollar, not a dollar. The 1964 Kennedy half is a 90% silver coin, but very common. The value would be only for the silver, about $15.00 as of 9-1-11.
If you turn the coin over and look at the denomination on the back you'll find that it's a HALF dollar, not a $1 coin.
50¢ Please look at the back of the coin. It's a HALF dollar. It's also made of copper-nickel, not silver.
Eisenhower is ONLY on the one dollar coins from 1971-1978. Kennedy has been on the US Half dollar since 1964. Look at the coin again and post new question.
Please check the coin again. If you look on the back you'll find that it's a HALF dollar, and if you look on the front you'll see that it shows a picture of Benjamin Franklin who was much older and balder than JFK ever had a chance to become. There's more information at the Related Question.
Either not Kennedy or not a dollar. Please look at the denomination on the back.