projectil question (1 Viewer)

[esther]

can u help me with this q?
a projectile is launched horizontally from a cliff 100m above the ocean with a velocity of 30ms-1
a) how long does it take to hit the water?
b) what is its velocity when it hits the water?

can u tell me which eqn to use

 

[superhubert]

s=.5at^2
so 100=4.9*t^2
so time=4.51sec...

v=u+at
so v=9.8*4.51
=44.198ms
v^2=30^2+44.198^2
so v=53.4ms

 

[spice girl]

Originally posted by esther
can u help me with this q?
a projectile is launched horizontally from a cliff 100m above the ocean with a velocity of 30ms-1
a) how long does it take to hit the water?
b) what is its velocity when it hits the water?

can u tell me which eqn to use

Just the equations:
a) Use y = ut + 1/2at^2
Consider vertical motion, of course
b) Use v^2 = u^2 + 2ay
v here is only vertical. So you must calculate total velocity, using vector addition of hroizontal and vertical acceleration

 

[superhubert]

@#$#% database errors...........
then v^2=30^2=44.198^2
=53.4ms