A car falls off a ledge and drops to the around in 0.7 s. (let g=$$10ms^{-2})$$ 
What is its speed on striking the ground?

A

9 $$ms^{-1}$$

B

8 $$ms^{-1}$$

C

4 $$ms^{-1}$$

D

7 $$ms^{-1}$$