Tutors Online

Just three Uni Students who can help you with some academic questions We can help with general Maths, Science and English up to grade 10, and higher level Biology, Chemistry, Physics and Mathematics. For BIOLOGY, request LILY. For CHEMISTRY, request either LILY or JAE. For PHYSICS, request either JAE or DR. MATHTASTIC. For MATHEMATICS, request DR. MATHTASTIC. We also have a fourth tutor who is an 'all-rounder' who will be assisting.

[highschooltuition]

Hey! I'm really struggling with physics. Here's one of the many problems: The moon has a mass of 7.36x10^22 kg and moves about the earth in a circular orbit of radius 3.8x10^8 m with a period of 27.3 days. Find the moon's kinetic energy as observed on earth. THANK YOU! I'd like whoever's best at physics! Either Jae or Dr. Math!

We know from circular motion that v=2ㅠr/T, as the speed would be the distance travelled divided by the take taken. Use this equation to find V:V = 2 x ㅠ x (3.8x10^8)/(27.3 daysx24x60x60) Remember that the SI units for time is seconds. This gives us V=1012.25 m/s, or 1.01x10^3 m/s.As we are asking to find the kinetic energy of the moon, substitute the V value into the equation: E(kintetic) = 1/2 x m x v^2E= 1/2 x (7.36x10^22) x (1012.25^2)This gives us E=3.77x10^28 J. 

Please feel free to ask us any more questions you may have :D-Jae.  

[highschooltuition]

Lily or Jae! I got pointed here by somebody in my ask box for chemistry help. My question is this. I need to balance the equation and anyway I put it, I have far too many hydrogens. It will probably be easy once I see the answer. Any suggestions and explanations? _C4H10(g)+_O2(g)->_CO2(g)+_H20(g)

When I quickly tried to balance the above equation, I got:2C4H10 + 13O2 ---> 8CO2 + 10H2OLet's now count all the molecules and make sure it's balanced. Carbons: 8 on the reactant side, 8 on the products.Hydrogens:  20 on the reactant side, 20 on the products.Oxygens: 26 on the reactant side, and (8x2)+10 = 26.Once everything matches up, you can be sure that your equation is balanced :DJust remember that there is no easy way of balancing equations very quickly, the best way you can balance these is by trial and error. I personally like to leave the elemental molecules last (02, H2 etc) as they can be easily manipulated without affecting another element. Thanks for your question, and please feel free to ask us anything!- Jae.  

[highschooltuition]

If you were to have lightbulbs in series and parallel and one light broke, why would the ones in series also go out and not in parallel?

When two light bulbs are in series and one goes out, the light bulb that has gone out has caused a open circuit. As a result the current and voltage no longer flows to the other light bulb. When two light bulbs are in parallel and one light bulb goes out there is still a loop where the current and voltage will travel. You can picture the parallel becoming a series circuit because the open circuit will be bypassed.

DR. MATHTASTIC :)

[highschooltuition]

Can you explain how you can tell how many C environments there are in an organic molecule?

If you're given a C-NMR spectrum, count the number of peaks that are present as this will equal the number of environments. If you've been given a diagram of a molecule and asked to count, here are some things you need to remember:-  Not each individual Carbon atom is a separate environment- What is bonded to a Carbon atom adjacent to the Carbon atom in question also affects the number of environments. In the above picture for example, 2-methyl-2-butanol has 5 Carbon Environments. Remember, 5 Carbon atoms doesn't necessarily mean 5 environments.While the 2 CH3 groups on the ends of the molecule are identical, we must look at the Carbon atoms next to them. The first C (enviro shown in dark blue) is bonded to another C(enviro is red) which is bonded to a Hydroxyl group and a Methyl group. This differs from the C on the last CH3 group as it's adjacent C is only bonded to a CH2 group. The remaining three Carbon environments should be easily spotted; 1 C bonded to 3 H, 1 C bonded to OH, and 1 C bonded to 2 H. Isopropyl Propanoate contains 6 C atoms, and possesses only 5 C enviros. The 2 Methyl groups(purple) are identical, and are also attached to the same carbon atom. This part of the molecule is symmetric, so the two Methyl groups are considered one environment. The other C atoms are obviously very different and bonded to different C atoms and environments. This gives us a total of 5 C environments. - Jae.