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

1) Two pieces of wood are glued together to form a long stick. The length of the

first piece is L1 = 0.97 ± 0.02 m, and the length of the second piece is

L2 =1.04 ± 0.01 m. What is the length (including uncertainty) of the stick?

2) An object of mass m = 2.3± 0.1 kg , is moving at a speed of

v =1.25 ± 0.03 m/s . Calculate the kinetic energy ( KE = 1/2 mv2 ) of the object.

What is the uncertainty in the calculated value of KE ?

*****************************************************

L_{1}+L_{2}= .97 + 1.04 ± Δuncertainty

Δu = sqrt(u12 + u22 + ...) = √ (.02^2+.01^2) =.0224

L_{1}+L_{2}= 2.01 ± 0.0224m

KE=0.5mv2 ± Δ u= 1.80±Δ

Δu=dX/X = sqrt( (dA/A)2 + (dB/B)2 +...) =

=dX/1.80 = sqrt( (0.1/2.3)2 + (0.03/1.25)2 )

=√.002466*1.80

=.0853

KE=1.80±.0853J

**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: Length and Value of KE Question. Please Check Answer

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