# suvat equations

A ball is dropped from rest from a hot air balloon. It hits the ground 15 seconds later.
a. Calculate the speed with which it hits the ground.
i. V = U + AT
V = 0 + 9.8*15
V = 147 m/s
b. Find the height from which the ball was dropped.
i. S = 0.5(U + V)T^2
S = 0.5(147)15^2
S = 16537.5
ii. V^2 = U^2 + 2AS
S = 1102.5 metres

Answer a is fully correct but only ii is correct for b. I really want to know why the first one didn’t work. I genuinely can't see what I've done wrong and I want to know how I can prevent this happening during a test.
Original post by honey_mgw
A ball is dropped from rest from a hot air balloon. It hits the ground 15 seconds later.
a. Calculate the speed with which it hits the ground.
i. V = U + AT
V = 0 + 9.8*15
V = 147 m/s
b. Find the height from which the ball was dropped.
i. S = 0.5(U + V)T^2
S = 0.5(147)15^2
S = 16537.5
ii. V^2 = U^2 + 2AS
S = 1102.5 metres

Answer a is fully correct but only ii is correct for b. I really want to know why the first one didn’t work. I genuinely can't see what I've done wrong and I want to know how I can prevent this happening during a test.

For b i, you squared 15 but you’re not supposed to. If you don’t square 15 you get 1102.5m
omlll

i swear i ALWAYS do this (missing a number/reading something wrong)

tysmm,, i would have never noticed (i think i wrote my other questions like this too smhh)

again, ty!!