KE-1/2mv^2 physics question

  • #1
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
 

Answers and Replies

  • #2
479
2
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).
 
Last edited:
  • #3
29
0
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
 
  • #4
Integral
Staff Emeritus
Science Advisor
Gold Member
7,215
62
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.
 
Last edited:
  • #5
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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