Problem 5 ! i need an equation to solve

When you drop a pebble from height a it reaches the ground with speed v if there is no air resistance. from what height should you drop it so it will reach the ground with three times the speed? (a) 9m (b) 3m (c) 6m (d) 18m

In order for the bug to fly through the air a force has to push the bug forward. identify this force. how does the bug produce

Which is not true about oxygen-17 and oxygen-18?