Help Needed: Solving Homework Equations Without Enough Variables

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SUMMARY

The forum discussion centers on solving physics homework problems involving work and force. The first problem involves calculating the work done by a pitcher on a baseball, given its mass of 0.145 kg and speed of 35 m/s, using the work-energy theorem. The second problem requires finding the force needed to stop a 2000 lb car over a distance of 100 ft, also utilizing the work-energy theorem. Participants emphasize the importance of understanding the work-energy theorem to solve these problems effectively.

PREREQUISITES
  • Understanding of the work-energy theorem
  • Familiarity with basic physics concepts such as mass, force, and distance
  • Knowledge of unit conversions (e.g., pounds to kilograms, feet to meters)
  • Ability to manipulate equations involving work (W = FD)
NEXT STEPS
  • Study the work-energy theorem in detail
  • Practice problems involving work and force calculations
  • Learn about unit conversions in physics
  • Explore examples of real-world applications of the work-energy theorem
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Students studying physics, educators teaching mechanics, and anyone seeking to improve their problem-solving skills in work and energy concepts.

krash91
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Hey guys, I'd love some help with these problems, its seems to me that there aren't enough variables.

Homework Statement


A .145kg baseball leaves a pitcher's hand at a speed of 35 m/s. If air drag is negligible, how much work has the pitcher done on the ball by throwing it?


Homework Equations


W=FD


The Attempt at a Solution


W=(MA)(VT)

Seems like I can't solve it without the time it was in the air.

And this one as well

Homework Statement


Find the force needed for friction in the tires of a 2000lb car to stop it in 100ft

Homework Equations


W=FD?

The Attempt at a Solution


Again, it seems like there aren't enough varibles. If I had the velocity of the car then it would make sense.

Some hints and nudges in the right direction would be great!
 
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welcome to pf!

hey krash91! welcome to pf! :wink:

for both questions, use the work energy theorem …

what do you get? :smile:​
 

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