(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

I am working on an AP physics project, and the assignment is to launch a golf ball accurately at close (10 - 15m) and long (50-60m) range. My group and I have decided on a spring based slingshot that will consist of a T shaped launcher with two springs (one on each side of the T) connected to a pouch. My question is about how to experimentally obtain a value e (efficiency).

2. Relevant equations

I know that Fs = -kx, so for two springs: Fs = -2kx

Integrate this to get the stored energy: Us = kx^2

I have researched some and found that an e is added to account for the efficiency at transferring this stored energy into kinetic energy, so: Us = ekx^2

And Kinetic energy: K = (1/2)mv^2

3. The attempt at a solution

Set k = Us

(1/2)mv^2 = ekx^2

mv^2 = 2ekx^2

v^2 = (2ekx^2)/m

v = ((2ekx^2)/m)^(1/2) meters per second

rearrange this to solve for e:

ekx^2 = (1/2)mv^2

e = (mv^2)/(2kx^2)

e is then the ratio of the actual kinetic energy of the golf ball to the stored energy in the spring for a given draw-length x.

My question is not so much about the math as it is how to find e accurately. I'm not sure what sensors can measure velocities upwards of 20m/s. Can e be accurately determined from one or two measurements at a low velocity?

Your input is greatly appreciated.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Spring-based Slingshot energy transfer

Can you offer guidance or do you also need help?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**