how can you tell when to use -9.8m/s^2 or +9.8 as your acceleration for a falling object? i have a problem that says " A ball is thrown upward from the top of a 25 m tall building." would that be -9.8 since the ball is being thrown up(+) and gravity is pulling it down?(-)(adsbygoogle = window.adsbygoogle || []).push({});

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

Dismiss Notice

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: -9.8 or just 9.8?

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