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KE-1/2mv^2

by truckerron1
Tags: ke1 or 2mv2
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truckerron1
#1
Jan28-06, 12:08 PM
P: 8
hi I am new and new to physics i am have alot of trouble with this problem

mass =1.3kg
41.5J
how do i get the velocity

so far i have it wrote like this
41.5J=1/2(1.3kg)(v)^2

but dont know how else to do plz help thanks ron
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z-component
#2
Jan28-06, 12:26 PM
z-component's Avatar
P: 483
The equation KE=1/2mv^2 says that the kinetic energy is equal to half of the mass of the object times the object's velocity squared. So you need to solve for velocity (v). Isolate the v variable using algebra (try to get v by itself on one side of the equation).
Eivind
#3
Jan28-06, 01:10 PM
P: 29
KE=1/2mv^2
41,5J=1/2*1,3*v^2
41,5J/(1/2*1,3)=1/2*1,3*v^2/1/2*1,3
63,8=v^2
sqrt(63,8)=v
v=7,98 m/s

Integral
#4
Jan28-06, 03:24 PM
Mentor
Integral's Avatar
P: 7,315
KE-1/2mv^2

You will find that it is easier to do your algebra BEFORE plugging in the numbers. You have

[tex] \mbox{KE} = \frac 1 2 m v^2 [/tex]
then
[tex] 2 \mbox{KE} = m v^2 [/tex]
then

[tex] 2 \frac {\mbox{KE}} m = v^2 [/tex]

so

[tex] v = \sqrt { 2 \frac {\mbox{KE}} m } [/tex]

Now you can substitute in your numbers and arrive at the numeric solution.
truckerron1
#5
Jan28-06, 03:41 PM
P: 8
thank you for the help i have been out of school 24 years and this is my last semester for my degree thanks ron


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