Physics Homework

I have a few questions that I don't understand and would like to get checked, please?

5.If energy is conserved and momentum is conserved, would they both have to be conserved simultaneously in some interaction?

My answer: No because each engergy and momemtum is being conserverd.

9. A 60 kg skydiver moving at terminal speed falls 50m in 1 s. What power is the skydiver expending on the air?

p=50m/1s=50 Watt

12.Where, exactly, does the energy stored in oil come from? How can we get "work" from oil? In your discussion, try to use the words work, energy, heat, power, and conservation in their correct physical sense.

-I don't understand this question.

1. The answer to 5. is yes, but some of the energy may be heat and not show up in equations of motion. Only elastic collision conserve (kinetic + potential) energy.

9. Your equation is wrong. You cannot divide distance by time to get power. At terminal speed,
(powerloss) = weight x velocity.
The average power for the one second is M g/(1 sec)

12. The energy from oil starts with chemical energy in the molecules that gets converted to heat in an engine (by reacting with oxygen), and then converted to mechanical energy when a piston is pushed by hot combustion products.

posted by drwls

Similar Questions

1. General

Please understand that I am not upset with anyone or whatever I just want to know something. I have some work to be checked and the regular tutors here say that "we will be happy to critque your thinking" right? Ok so when someone
2. Variation-Questions

I have some questions that I don't understand and need to be checked please? Slove the problem. 1. y varies directly as z and y=187 when z=17. Find y when z=15 -This is how I did it: 187=k*17, I divided by 17 on both sides and got
3. Math

My child's teacher sent out questions to prepare for a big math test. He does not understand the questions well and I can't seem to get him to grasp it. I know the answer but could you show some easy methods or something, thank
4. general

I really don't like the fact that you guys are skipping so many questions we need help here and were not getting it. i understand that no one knows everything but, please don't skip the questions its really hard when i need help
5. To all students

Please be patient when you post questions. Please, especially, don't post questions that need answers checked within a short period of time. There is no guarantee that the tutor who addresses your subject is online at any
6. Algebra

I have a few more questions that I either need help with or just need checking. Is the algebraic expression a polynomial? if it is write the polynomial in standard form, 1. 6x-9+8x^2 I got Yes; 8x^2+6x-9 Perform the indicated
7. math-moneyfractions

i have some math questions that i really ,really,need help with asap if any body can explain some of these questions that will be great help.Ok here are 3 of the questions i am about to type now ok the first one says,whole 16
8. To Troyer 0269

I deleted your last science post, as I promised I would a couple of weeks ago. You posted five questions that I'm sure you could answer by reading your text. As you know, we don't give answers, but help students with problems they
9. Science

I have some equations that I would like checked. Thanxs! 1. An automobile starts from rest and accelerates at 3m/s2 for 4 seconds. How fast is it going after acceleration? 3m/s^2 / 4 = .75 m/s 2. If an automobile travels at 30