Is the Velocity negative or positive?

In summary: The final velocity of the log at impact will be 55.4 m/s towards the centre of the Earth. The distance it falls will be approximately 162.54 feet. In summary, the velocity of the log at impact is 55.4 m/s and the distance it falls is approximately 162.54 feet.
  • #1
rasofia77
22
0
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Homework Statement


If you were to throw a large log over the edge of the Grand Canyon and it took 5.65 seconds to hit the ground, calculate the velocity of the log at impact in m/s and calculate the distance the log fell in feet.[/B]

Homework Equations


vf=vi+at[/B]

The Attempt at a Solution


So I get vf=(9.8)(5.65)= 55.4 ...But then I think about it, and the object is going downwards so shouldn't it's velocity be negative (South)..? Also, is 9.8 supposed to be positive or negative?[/B]
 
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  • #2
You can choose g to be positive or negative, whichever you wish. The final velocity here will take on whatever sign you give to g. The important thing is that you remain consistent! :)
 
  • #3
NascentOxygen said:
You can choose g to be positive or negative, whichever you wish. The final velocity here will take on whatever sign you give to g.

So there's always two right answers?
 
  • #4
rasofia77 said:
So there's always two right answers?
Not really. It's final velocity is 55.4 m/s towards the centre of the Earth. That's one answer. :)

I'd be concerned about your omission of the units when talking of velocity, though.
 
  • #5
NascentOxygen said:
Not really. It's final velocity is 55.4 m/s towards the centre of the Earth. That's one answer. :)

I'd be concerned about your omission of the units when talking of velocity, though.

Sorry, haha *m/s. One last question, is acceleration the same for all objects?
Well, it is, due to gravity (9.8m/s^2) ..but then again I get confused because there's so many different word problems with different accelerations as answers, obviously. What would be the final, true answer though?
 
  • #6
rasofia77 said:
Sorry, haha *m/s. One last question, is acceleration the same for all objects?
g is the same for all objects in a particular location. Whether the object is accelerating depends on the net force. Gravity is only one of many forces that may be acting simultaneously on an object.

Well, it is, due to gravity (9.8m/s^2) ..but then again I get confused because there's so many different word problems with different accelerations as answers, obviously. What would be the final, true answer though?
The answer to what?
 

FAQ: Is the Velocity negative or positive?

1. Is a positive velocity always greater than a negative velocity?

No, the magnitude of a velocity determines its size, not its direction. A negative velocity can have a larger magnitude than a positive velocity.

2. How do you determine the direction of a velocity?

The direction of a velocity is determined by the sign of its value. A positive velocity indicates motion in the direction of the reference point, while a negative velocity indicates motion in the opposite direction.

3. Can a velocity change from positive to negative?

Yes, a velocity can change from positive to negative or vice versa if the direction of the object's motion changes. For example, a car moving forward with a positive velocity can change to a negative velocity when it starts moving backwards.

4. What does a negative velocity represent?

A negative velocity represents motion in the opposite direction of the reference point. It can also indicate a decrease in position or speed over time.

5. Does a negative velocity always indicate a decrease in speed?

No, a negative velocity does not always indicate a decrease in speed. It can also represent a constant speed in the opposite direction of the reference point.

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