A little over 10.25 grams of pure silver.
The weight is 12.50 grams.
1949 would be a Franklin half dollar, which weighs 12.5 grams and is 90% silver, giving it 11.25 grams of silver per coin. It's currently (as of 7 September 2012) worth about $12.
It really depends on the date and condition.
A U.S. fifty cent piece dated 1961 is a Franklin half dollar. The coin is not rare, if it shows any wear the value is about $12.00 just for the silver.
About $12.00
About $2.00 only for the silver.
14oz
A '60 Franklin half is worth about $11-12.
1966 Kennedy half dollar is 40% silver and valued at about $2.50 for the silver.
The coin has NO silver and is face value.
A US fifty cent coin, or half dollar, is 30.6 millimeters in diameter. Weights of these coins vary depending on year of mint--previous to 1965 the weight is 12.5 grams. 1965 to 1970 the weight is 11.5 grams, and from 1971 forward they weigh 11.34 grams.
The last Franklin half dollar was dated 1963.