# Finding velocity when onlu a mass and acceleration is given

## Homework Statement

The instruments attached to a weather balloon have a mass of 5.0kg.The balloon is released and exerts an upward force of 98 N on the instruments. I have found that the acceleration is 1.96 m/s/s by F=ma.
After the balloons have accelerated for 10 seconds, the instruments are released. What is the velocity of the instruments at the moment of their release?

## Homework Equations

V(sub f)^2=V(sub i)^2 + 2ad
I have tried this but I don't know either velocity or the distance.
or would it be:
V(sub f) = V(sub i) +at

## The Attempt at a Solution

V(sub f)^2= 0^2 + (2)(1.96m/s^2)(d)
or
V(sub f)= 0 + (1.96m/s^2)(10s)

## Answers and Replies

Pengwuino
Gold Member
Be careful, that's not the acceleration. How did you figure out what the acceleration was?

Once you know the acceleration, you also know that

$v = v_0 + at$

It's assumed to be released from rest, so $v_0 = 0$. It's a simple matter of letting $t = 10 sec$. Remember, the question is quite simple since it only asks for what happens at the release.

Oh okay. I looked at the calculator wrong for the decimal. So the initial velocity is 0?

The force exerted by the balloon on the instruments is 98N, but what is the net force after accounting for gravity?

is it 10?

How did you arrive at that? E.G. which equation did you use?