What is the average velocity of the object as it falls to the ground?

Can you find that?In summary, the object is dropped from a height of 25m, with an acceleration of -9.8 m/s^2. Using the kinematic equation vf = vi + at, we can find the final velocity just before the object hits the ground. With a time of 2.3 seconds, we can calculate that the average velocity of the object as it falls to the ground is -10.8 m/s.
  • #1
1irishman
243
0

Homework Statement


An object is dropped from a height of 25m above the ground. What is the average velocity of the object as it falls to the ground?


Homework Equations


d=vit+1/2at^2


The Attempt at a Solution


d=-25
a=-9.8
vi=0

-25=-4.9t^2
t=2.3s
vavg=displacement/time
-25/2.3=-10.8m/s
the answer in book says a=-11.1m/s i don't understand, please help?
 
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  • #2
Use the 2.3 s time of flight to find the velocity just before the object hits the ground. Half of that (because the starting velocity is zero) is the average velocity.
 
  • #3
I still don't understand, how does that get plugged into the formula? What formula do I use?
Thank you
 
  • #4
Use the kinematic equation that gives you the velocity of an object at any time t.
 
  • #5
v=d/t right?
 
  • #6
Nope. That equation is valid only when the acceleration is zero. Here the acceleration is g down. What equation do you know that relates the initial and final velocity to acceleration and time?
 
  • #7
a=vf-vi/t right?
 
  • #8
That's the one. You know everything except vf.
 

Related to What is the average velocity of the object as it falls to the ground?

1. What is average velocity?

Average velocity is the measure of the change in an object's position over a specific period of time. It is calculated by dividing the total displacement of the object by the total time taken.

2. How is average velocity different from instantaneous velocity?

Average velocity considers the overall change in an object's position over a given time period, whereas instantaneous velocity is the measure of an object's velocity at a specific moment in time.

3. How is average velocity calculated for a falling object?

The average velocity of a falling object can be calculated by dividing the distance the object has fallen by the time it took to fall. This is assuming that the object is falling with a constant acceleration due to gravity.

4. Is average velocity affected by the mass of the falling object?

No, the average velocity of a falling object is not affected by its mass. This is because all objects, regardless of their mass, will experience the same acceleration due to gravity.

5. Does air resistance affect the average velocity of a falling object?

Yes, air resistance can affect the average velocity of a falling object. If the object is falling through a fluid medium, such as air, the force of air resistance will act against the object's motion, causing it to slow down and potentially changing its average velocity.

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