ScreamRide

Got this on the 2nd demo level. Aim low at near right building to hit the explosives on the bottom. For me that chain-reactioned to the middle building. Then I hit the explosives at the bottom of the building on the left and then the one on the far right. Achievement popped when the level ended during summary screen which suggested I had 41 explosives so it looks like this one should be pretty easy to get on that level.