a) Check all of the following that are correct statements, where E stands for ym
ID: 584091 • Letter: A
Question
a) Check all of the following that are correct statements, where E stands for ymc2. Read each statement very carefully to make sure that it is exactly correct The definition of work is w = The definition of work is w = FAx + FAy + FAZ. | The definition K = E-mc2 is valid even for speeds near the speed of light O At speeds close to the speed of light, kinetic energy is approximately equal to (1/2)mv2 O The definition of work is W = F.y, F., The definition of work is W FAx, FyAy, FAz >. The energy principle can be written Ess-Wsum The energy principle can be written Esysf Esysi+Wsurr Wsurr. (b) An object with mass 80 kg moved in outer space. When it was at location its speed was 10 m/s. A single constant force N acted on the object while the object moved to location m. What is the speed of the object at this final location? final speed = m/sExplanation / Answer
xi = 6i -35j - 7k
xf = 9i - 43j - 12k
displacement r =xf - xi = 3i - 8j - 5k
F = 230i + 460j - 140k
Work done by force = F.r
= (230i + 460j - 140k ). (3i - 8j - 5k )
= (230 x 3) + (460 x -8) + (-140 x -5)
= -2290 J
using work energy theorem,
work done = change in KE
-2290 = m (vf^2 - vi^2 ) /2
-4580 = 80 ( vf^2 - 10^2)
vf^2 - 100 = -57.25
vf = 6.54 m/s
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