Question

A bike has an inertia of 10.04 × 1237 mg•m3 and a mass of 7.2 × 1094 kg. Based on this, what is the bike rolling down's radius?

Answer 1

@Nnesha @pooja195

Answer 2

@Mashy

Answer 3

Do you know what is the expression for Moment of inertia of a solid sphere?

Answer 4

I=2/5 MR^2 correct?

Answer 5

that is correct.
Mass is given to you
and I is given to you
so can't you just substitute and solve for R ?

Answer 6

i got R=93442.8, but i don't think thats right

Answer 7

No, that isn't..
Just crunch in the numbers carefully

Answer 8

what?

Answer 9

i got 9.74x1037=2/5(r)^2

Answer 10

and mass in there

Answer 11

it is 10 power 37, hope you plugged that in correctly and then took the square root!

Answer 12

ok ill try one more time and see what i get hold on please

Answer 13

do i have to use the m^2 in the moment of inertia??!

Answer 14

ok, this time i got R= 9.28, am i getting there? @Mashy

Answer 15

Nope

Answer 16

ok well I obviously need help, could i get some please???

Answer 17

Do step by step..

\[R^2 = \frac{5I}{2M} = \frac{5 \times 9.74 \times 10^{37}}{5.98 \times 10^{24}}\]

Answer 18

where'd you get the r^2

Answer 19

Crunch in the numbers and tell me what number pops out for R square?

Answer 20

In the moment of inertial equation buddy!

Answer 21

i got a really crazy number for my answer... for the second part of the equation only though i got: 8.14x10^64 :-(

Answer 22

I forgto to put a 2 in the denominator

But I guess your calculator is broken, or you don't know how to use it :P

Answer 23

you are sort of rude... you are here to help not insult me on how your physics are superior to mine, you are a teacher not showing off what you can do. i asked for help, obviously i don't know how to do it or i wouldn't be asking for your help!

Answer 24

Oh, I am not trying to be rude, I am just not sure, how to show you to put numbers in the calculator

Answer 25

ok well I asked for help so obviously I am going to not know exactly how to do it, otherwise I wouldn't be asking. Sorry if me not knowing is annoying, but thats why Ia m here

Answer 26

Tell me what answer you get for R^2???

Answer 27

I am not sure because thats what I am trying to figure out. first i did 5×9.74×10375.98×1024 part of the equation and got an absurd answer of : 8.14x10^61 and i don't know what to do next

Answer 28

But that is wrong..
I forgot to put a 2 in the denominator

and secondly

the powers must be SUBTRACTED

Answer 29

oh ok, sorry!

Answer 30

\[R^2 = \frac{5 \times 9.74 \times 10^{37}}{2 \times 5.98 \times 10^{24}}\]

Answer 31

now i got 1.32 x10 ^54...

Answer 32

No it is
\[4.07 \times 10^{13}\]
:-/

Answer 33

oh, the two 10's simplify to one ok

Answer 34

so now what?

Answer 35

Now take the root

Answer 36

how do i do that again? sorry....I am in middle school but have to take this

Answer 37

Are you using a calculator?

Answer 38

yes

Answer 39

Is there a button which says
\[\sqrt .\]

Answer 40

yes

Answer 41

That is the square root, but you got to make the ten power even. Can you try that?

Answer 42

do i hit square root button and then enter 4.07 x 10^13?

Answer 43

That depends on the type of calculator

And before you do, please convert that number into an even power of 10, PLEASE, PLEASE DO THAT!!!

Answer 44

how? sorry

Answer 45

I ll just give you the answer.

This planet is our home planet!
So google the radius of earth, ,problem solved TADA!!!

Answer 46

please, i really do need help but this problem is really hard for me in only 7th grade but advanced

Answer 47

You need to watch some Khan Academy videos on math.
You have math problem, not physics. You need to work on that.

Answer 48

please i need help just really with this problem :-( I'm jut going to keep asking on here for help so its not helping by leaving me

Answer 49

Parth, this is all yours!

Answer 50

:-(

Answer 51

Don't worry, Parth is awesome! :P

Answer 52

he left@

Answer 53

did you learn solving equations in math?

Answer 54

okay
\[300 = 3 \times 10 ^2 = 30 \times 10^1 = 300 \times 10^0 = 0.3 \times 10^4 = 0.03 \times 10^5\]

does that make sense?

Answer 55

oh pellet lol
wait.. typo!!

Answer 56

yes

Answer 57

\[I = \frac{2}5 MR^2\]\[9.74\times 10^{37} = \frac{2}5 \times 5.98 \times 10^{24} \times R^2\]Can you solve this equation?

Answer 58

\[300 = 3 \times 10^2 = 0.3 \times 10^3\]

Answer 59

I subtract the exponents right? @Mashy @ParthKohli

Answer 60

yes@!!!

Answer 61

ok so far I have- 9.74x10^37=23.92xr^2

Answer 62

@Mashy

Answer 63

k