Algodoo

i've done this bomb way to many times, if you keep them all in one piece, the explosion would get bigger.
also, if you want to make an activation bomb using this kind of bomb:
-make a circle of your choice.
- put a circle smaller than the first one and fix it to the first circle.
- copy the small circle with the fix (only), and past it on top of the others

also, how you want it to activate:
on ground hit - make the outter circle coll grp (x), and make one extra plane on top of the old one, and set it to coll grp (x), so the outter circle gets killed when it hits the ground.

on keypress - simply what i just said, select the outter circle and set it to a delete key, so it explodes when you want to.

for your lazyness building this one, only create-copying, i'll only give you a 3/10