No, you trade the warrant and the warrant price of $11.50 for one stock.
The warrant is a little like an option, but with a longer term.
If you buy a IPOA.WS warrant then that warrant gives you the option to buy one share of class A stock at $11.50 at a future date. If in the future, the stock is worth $20, then you make $20 - $11.50 - per share. If you buy one IPOA.U, then you get 1/3 of a warrant and 1 share of stock, the warrants will be useless unless you buy in groups of 3 for the IPOA.U. I didn't see the timeframe of the warrant, they're usually good for 10+ years, and they're currently trading in the $1.5-1.8 range.
To confirm, here's a decent article about how warrants work:
http://www.investopedia.com/articles/04/021704.asp