Question

a rock is dropped into a well hits the water in 5 secs. if there is no air resistance, what would be the rocks final speed?

Answer 1

Here u= 0m/s t=5sec v=? From newton's first equation of motion- v=ut v= 0* 5=0m/s

Answer 2

The acceleration of gravity is 9.8 meters per second².

So, 5 seconds after beginning from zero speed, its speed is (5 x 9.8) = 49 m/s² .