A small wooden block with mass 0.875kg is suspended from the lower end of a light cord that is 1.80m long. The block is initially at rest. A bullet with mass 0.0100kg is fired at the block with a horizontal velocity v0 . The bullet strikes the block and becomes embedded in it. After the collision the combined object swings on the end of the cord. When the block has risen a vertical height of 0.700m , the tension in the cord is 4.86N.
What was the initial speed v0 of the bullet?