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The kinetic energy in joules, of a moving object is found by using the formula E=1/2mv(squared), where m is the mass and v is the speed of the object. The mass of a car is 1.59 x 10(to the third)kg. The car is traveling at 2.7 x 10 (1) m/s. What is the kinetic energy of the car?
Seriously? Are you kidding me? They expect an 8th grader to get that problem? They expect a mom to get it too? Max and I are stumped. Oh I really did get this stuff at one point in my life. Any great mathematicians out there? (Max is hoping…)
33 comments
It sounds more complicated than it is, really!! You're just plugging into the equation…
If m is the mass and the mass is 1.59… and v is the speed and the speed is 2.7… your equation is:
E = 1/2 x (1.59 x 10^3) x (2.7 x 10)^2
Does that help or do I need to keep going? (I'm a math nerd–my degree was math education, though I haven't really "used" it for 7 years now!)
i am so not looking forward to our girls being old enough to ask for help with real math! they will be going straight to thier mechanical engineer daddy for help! sorry i'm not writing to help….but i feel your pain. 😉 good luck!
What Sarah said. 🙂
If that makes sense, stop reading… but if you need another way to look at it, it might help to keep in mind you're looking for an answer in Joules.
http://en.wikipedia.org/wiki/Joule (the important part is that first equation, where it says kg *m ^2 over s^2)
In this case, you can just plug into the equation. Take one half of the weight times the speed times the speed again. (kilograms * meters/second * meters/second… so you end up with Joules!)
Please delete this if you don't want to see the answer (or what I think is the answer)
One way is to change the scientific notation into standard notation:
m = 1.59 x 10^3 = 1590
v = 2.7 x 10^1 = 27
Now going to the formula:
E = 1/2mv^2
Plug in the numbers for m and v
E = (1/2) x 1590 x 27^2
E = (1/2) x 1590 x 729
therefore
E = 579555 which is the same as 5.79555 x 10^5
All I have to say is this makes me love blogging and the internet. 🙂
Wow! Look at all these replies already. I'll just leave encouragement…
Go Max!! Math is fun!
What language is this?
I think it must be foreign.
1/2 (1.59×10^3) (2.7×10^1)^2=
579.555kj or about 580kj
And don't think for a second that I had anything to do with this. My husband figured it out. I failed highschool algebra.
Oh man I'm so glad I'm past even having to help with 8th grade math! These answers are truly amazing! What a team of helpers!
My daughter is in 5th grade & I can't help her with her math. I'm hoping we can find a good tutor for her too 😉
i came to comment and help too, but I see you already have a couple of good answers. Don't be scared! The numbers look big, but it's not hard.
You can do it!
I love your readers!
This is where I turn the stuff over to Dad. But your dad is probably with our dad 🙂
I remember thinking "After I get out of school, I'll never use this stuff again … no matter what some teacher says." And I haven't.
haha,I tutor this at tutor.com, but who needs it when you have readers like this! They just saved you like $10 dollars for the 15 minutes it would have taken! 🙂
oh man…I am having a problem with 6th grade math…I am in big trouble! 😉
Oh my goodness, this is the most hilarious comment thread I have ever read! I can't believe you just got help with homework via the blogosphere! Awesome!
If it is any consolation, my daughter and I recently spent well over an hour on a 6th grade math problem. Finally, I conceded defeat and brought my aerospace engineer husband in to help. Even HE couldn't explain how it should be done!
Wow, I guess we don't need a tutor after all…just a blog with wicked-smart readers 😉
Max is off to school with his homework all done and tucked safely in his backpack thanks to help from you! Thank you from both of us!
It's funny because right before Max and I posted that last night Dave said almost verbatim what Sarah said in the first comment. When Max read it to me I thought Dave was pulling a prank on us.
He talked the big talk and told us it sounds more complicated than it is, but he couldn't actually DO it, so thanks everyone!!
By the way, this is what it says about Joules when I looked it up:
"The joule (pronounced /ˈdʒuːl/ or /ˈdʒaʊl/); symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended (or work done) in applying a force of one newton through a distance of one metre (1 newton metre or N·m), or in passing an electric current of one ampere through a resistance of one ohm for one second. It is named after the English physicist James Prescott Joule (1818–1889).[1][2][3]"
Hmmmm…still not speaking my language. Something that tells me to pronounce "joule" like this: /ˈdʒuːl/ or /ˈdʒaʊl/ is way out of my league. What in the world are those little symbols anyway??
I think my brain might be melting.
Thanks again everyone!
Haha sorry about that! I was referring to this equation:
https://img.skitch.com/20110224-rjfmq6g6ksp1yeiwuip5p52hde.jpg
I have no clue what that pronunciation mumbo jumbo is about!
Maybe it would have helped if I actually LINKED it: this equation 🙂
Times like this make me grateful that I married a math/science nerd and that I am an English nerd. Hopefully I won't have to deal with math like this at homework time and he'll never have to help write a paper. Gotta love the wisdom of the internet- hope you guys figured it out in time!
I never had all this in Math.We used to these problems in Physics. Its pretty easy if you remember the formula and put in the values.Most important is to remember the units.
Thankfully being an Asian Indian has some perks..I used to love Maths and Science.Can't say the same about history!!
Oh Anne, you are so cute. I've just come to grips with the fact that math is not my forte! I was thinking through the fact that I took AP Calculus in high school, but realized it was only for a few weeks. When I realized I didn't need it for graduation I pulled myself right out of there. I figured I'd NEVER use all that funky math. But here I am with and 8th grader and now I need it!
Are you smarter than a 5th grader? Ha ha–I'm not! Glad you got your answer! 🙂
That's funny. I tried Calculus or maybe it was only pre-calculus, I can't remember now. I lasted only a couple weeks, too. Love the internet.
I'm zero help with math… but as a speech-language pathologist, I can tell you that those are phonetic symbols. While the American alphabet uses the same letters to represent several sounds- the phonetic alphabet is international and there is only one symbol to correlate with one sound and vice versa. Thus there is never any confusion on how something is pronounced. I don't haved an IPA (international phonetic alphabet) font on my computer (I did back in my grad school days) to show this easily- but that little d3 thingy represents the "j" sound & that little u looking symbol represents the same vowel sound you would hear in the word "put" or "foot"… case in point- there is a perfect example of using completely different symbols to represent the same sounds in our confusing English language. I love this blog btw.
Oh my. My brain just liquified and dribbled out of my ears. Good luck! LOL
Hey Shawni… my son Dallin is the resident math whiz in our home. He didn't get his abilities from his parents… math smarts skipped a generation! =) As a senior he is Highland's Math Club President and taking Calc. 2 at CGCC right now. Crazy huh? So if Max ever needs help he should give Dallin a holler.
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