projectile motion please help (1 Viewer)

[shantu1992]

3. a ball is projected vetrically upwards with a velocity of 24.5ms-1 from a position 50m high. How long will it be before it reaches the ground below and what will be its velocity just before it hits the ground?

9. a stone is dropped from a cliff .. wait TALL cliff and 1 second later another stone is projected vertically downwards with a velocity of 6 ms-1. if the ball raeches the sea in 8 seconds, what is the height of the cliff?

 

[cutemouse]

3. a ball is projected vetrically upwards with a velocity of 24.5ms-1 from a position 50m high. How long will it be before it reaches the ground below and what will be its velocity just before it hits the ground?

v=u+at
0=24.5-9.8t
t=2.5

9. a stone is dropped from a cliff .. wait TALL cliff and 1 second later another stone is projected vertically downwards with a velocity of 6 ms-1. if the ball raeches the sea in 8 seconds, what is the height of the cliff?

I don't get this question... I'm just going to calculate the 2nd stone that was projected downwards...

EDIT: Did something terribly wrong. Correct calculations:
S=ut+(1/2)at²
=(6*8)+[(1/2)*9.8*64)
=361.6m