Hi.(adsbygoogle = window.adsbygoogle || []).push({});

There is a hot air ballon with total mass M. There is an upward lift force of 2Mg/3 but the balloon is accelerating downward at a rate of g/3. The passenger needs to make the balloon lighter and starts throwing things of. What fraction of the total weight must he drop overboard so that the balloon accelerates upward at a rate of g/2.

I come up with the fact that the upward lift force must equal the weight plus the acceleration. But I get a wrong answear. The correct answear is 5/9. Can someone give me a hint to this problem please.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Need help with hot air balloon

**Physics Forums | Science Articles, Homework Help, Discussion**