a ballon is at a height of 12.8m above the ground and ascending with a velocity of 12m/s ..a 2kg body is dropped from it .it will reach the groundd in (g=10m/s^2)

Question

alexwee123 · Answer

so what's the question?

anonymous · Answer

i think in how many seconds...

anonymous · Answer

I think the question is to find when it will reach the ground.

anonymous · Answer

we have to find the time?

anonymous · Answer

Wait, when is the weight is detached from the balloon?

anonymous · Answer

the ans=3.2s  plzz solve for it..........

anonymous · Answer

just use s=ut + 0.5 at^2
s= -12.8, u=12, a = -10
solve this 
$$5t^2 -12t -12.8 = 0$$

anonymous · Answer

got it?

anonymous · Answer

the reason we use s=-12.8 is because we set the upward motion as a positive value. hence when the stone is dropped from the ascending balloon, the stone is actually moving upwards with the same speed as the balloon. hence v=positive as it's moving upwards. for a it's a negative value because the gravity is pulling the stone down hence halting the stone from moving anywhere further upwards. hope you get the concept behind.

anonymous · Answer

yes i got it