1. ## An object...

An object is dropped from a helicopter. When it reaches terminal velocity
1) the acceleration finally reaches g.
2) the acceleration of gravity, g becomes 0.
3) the total force is zero.
4) all of the upward forces add uo to zero.
5) gravity no longer acts upon it.

2. Originally Posted by babygirl
An object is dropped from a helicopter. When it reaches terminal velocity
1) the acceleration finally reaches g.
2) the acceleration of gravity, g becomes 0.
3) the total force is zero.
4) all of the upward forces add uo to zero.
5) gravity no longer acts upon it.
I think the answer is #2

3. Originally Posted by babygirl
An object is dropped from a helicopter. When it reaches terminal velocity
1) the acceleration finally reaches g.
2) the acceleration of gravity, g becomes 0.
3) the total force is zero.
4) all of the upward forces add uo to zero.
5) gravity no longer acts upon it.
Sorry Quick, this is twice in one night!

The answer is 3). If an object is a terminal velocity that means the velocity is constant. This implies there is no acceleration. By Newton's second, if a = 0, then the net force on the object is zero. (This is not quite the same as saying that all the forces on the object are zero.)

Specifically, the acceleration due to gravity, g, is always the same on an object...9.8 m/s2 downward...no matter what circumstances we are talking about. (Note: I'm ignoring problems involving large heights above the Earth's surface where we need to be using Newton's Law of Gravity!)

-Dan

4. Originally Posted by topsquark
Sorry Quick, this is twice in one night!
Darn! I need to brush up on my physics...

5. Originally Posted by Quick
Darn! I need to brush up on my physics...
Don't feel so bad, Quick. I won't say these two questions are trick questions, but they ARE designed to pit your physical intuition against your knowledge of specific definitions. Simply put they are not designed for answering without a great deal of logical thought. (As I've been answering such questions for the last 15 years, it was easy for me. It wouldn't be for a student.)

-Dan