How to incorporate the initial vellocity

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In summary, the conversation is about finding the average force exerted by a shot-putter on a 7.0 kg shot. The formula F=ma is mentioned and the variables are explained. The final velocity, initial velocity, acceleration, and displacement are all used to solve the problem. The correct answer is determined to be 210 N, with a minor error in rounding. The issue of forgetting to square the initial velocity is brought up and resolved, resulting in the correct answer.
  • #1
kbrowne29
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I'm having difficulty with the following problem: What is the average force exerted by a shot-putter on a 7.0 kg shot if the shot is moved through a distance of 2.8 m and is released with a speed of 13 m/s.

I know that I have to use the formula F=ma. The mass is obviously 7.0 kg, but I don't know how to find the horizontal component of the acceleration of the shot. I don't know how to incorporate the initial vellocity and the distance the shot travels. I would appreciate any help. Thanks.
 
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  • #2
Use the formula:

v2 = u2 + 2as
 
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  • #3
what do the variables stand for?
 
  • #4
v is final velocity (13ms-1), u is initial velocity (assume this to be zero), a is accleration, s is displacement (distance).
 
  • #5
ok, so that gives an acceleration of 2.32m/s^2. But it doesn't make sense that this would be the acceleration to plug into the formula F=ma. I know that the correct answer to the problem is 210 N.
 
  • #6
Show me your workings, using the above equations I got an answer of 211.25 N (210 N if I'd rounded the accleration to 3 ms-2).
 
Last edited:
  • #7
I got it! I've been making such a dumb mistake. When I used v^2=u^2 + 2as, I kept forgetting to square the 13! Now I'm getting the right answer. Thanks a lot for helping me out here.
 

1. How do I calculate the initial velocity?

The initial velocity can be calculated by dividing the displacement (distance traveled) by the time taken to travel that distance.

2. What are the units of initial velocity?

The units of initial velocity are meters per second (m/s) in the SI system and feet per second (ft/s) in the imperial system.

3. How do I incorporate the initial velocity into my experiment or calculation?

To incorporate the initial velocity into your experiment or calculation, you need to include it as a factor in your equations or use it as a starting point for your measurements.

4. Is initial velocity the same as initial speed?

No, initial velocity and initial speed are not the same. Initial velocity is a vector quantity that includes both the speed and direction of motion, while initial speed is just the magnitude of the initial velocity.

5. Does the initial velocity affect the final outcome of an experiment?

Yes, the initial velocity can affect the final outcome of an experiment. It is an important factor in determining the motion and behavior of objects and can impact the results of an experiment or calculation.

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