You throw a ball with a mass of 182.2 g, with a speed of 4.6 m/s. Calculate the kinetic energy in Joules to 3 s.f. ,
and what is the uncertainty C=1 (Unsure: <67%) C=2 (Mid: >67%) C=3 (Quite sure: >80%)?
KE=(1/2)mv²
=(1/2)*0.1822*4.6²
=1.9276
=1.93 (3 significant figures)
To calculate the uncertainty,
we do a partial differentiation with respect to m and v, and multiply by the maximum errors of δm=0.00005kg and δv=0.05 m/s.
δKE=(1/2)v²δm+mvδv
=(1/2)4.6²*0.00005+0.1822*4.6*0.05
=0.042 joules
or
Kinetic energy = 1.928±0.042 J
Therefore the third figure of the above answer is not reliable (as expected).
Don't know what it means by the uncertainty percentage.