By default, the Nikon D7000 (and many other Nikon DSLRs) have a maximum flash sync speed of 1/250. Luckily, there is an easy way to override this. In many situations, this is plenty fast but there are occasions when you need extra light to capture something in motion in poor lighting or you may not like the sunlight and want to control your own light source. It's not hard to do but it's a pain to realize you need this in the field and not know how to do it. Note: This worked perfectly on my Nikon D7000 and SB-700. Here is proof at 1/8000. I assume it works on other modern Nikon DSLRs and flashes but I can guarantee it. Also, even though you can leave your camera and flash in TTL, you may need to take manual control of the flash to get the desired result. On your D7000, head into the Custom Settings Menu.
Select e. Bracketing/flash.
Select e1. Flash sync speed.
Now select 1/250 s (Auto FP).
Now you will be able to set your shutter speed above 1/250 in Shutter Priority mode or Manual mode. If you just need it to work, you're done. If you want to know why Nikon sets a default limit, read Ken Rockwell's rant post about it.