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  1. M

    Work Done on a Block Dropped onto a Spring

    Well, in question B. they ask for the spring force which is in units of Newtons. The units in your answer are in joules, but you need them to be in Newtons in order for the answer to make sense.
  2. M

    Help with freefall problem please.

    I think you've got the right idea. You want to split it into two problems; one for going up, and the other for coming back down.
  3. M

    Help with freefall problem please.

    We don't do that here. However, if you show the work you've already done on this problem, people will point out your mistakes and help you solve your own problem.
  4. M

    Science Fair Project,

    First ask yourself why you believe this would actually happen. Why would the teen time be less than the adult time? The answer to this question should also give you some ideas for a keyword search.
  5. M

    Homework talking about time

    Look in the section of the book which is associated with that homework set. 'Usually' the information you need is contained in the chapter preceding the question. What topics are you currently learning from your textbook?
  6. M

    Physics Audio Tapes

    You could try the math and science tutorial section, or the links here at PF. I don't know if there would be any audio tutorials. You might want to check out your community or university library. Also, try asking local bookstores if they carry such products.
  7. M

    Solve it: Catch the Bus with Constant Velocity?

    Try drawing two pictures; the first showing the initial conditions, and the second showing the final conditions when you've caught the bus. Once you've drawn the pictures, make sure you listed all your knowns. List your kinematics formulas so you can see what you have to work with...
  8. M

    2 internal reflection questions

    You sound like you're on the right track with the first problem. As for the second, you're given a side and an angle. Draw a picture and think about right triangle trig.
  9. M

    I with Mechanical Energy, please

    Actually, your total mechanical energy, denoted by E, is a constant in a conservative system. E = U + K, where U = potential energy, K = kinetic energy. Your formulas for U and K are correct as well. The Ei = Ui + Uf comes from conservation of energy, but what you have is not quite...
  10. M

    Tell me what integrals are

    hi, The same thing also happened to me when I took physics and calculus concurrently. This is an oversimplification, but hopefully it will enough for now. There are two types of integration; definite and indefinite. Indefinite integration (also known as anti-differentiation) does...
  11. M

    Why We Store Fat Near Stomach & Buttocks: Forces & Advantages

    I'm just speculating here, but I think the location of fat deposits should have something to do with maintaining a stable body temperature, however I'm sure there are a ton of explanations out there as to why we're built the way we are. Maybe someone with a background in biology should...
  12. M

    Ear Damage from a Small Firecracker

    No, sound waves are spherical waves and travel in three dimensional space.
  13. M

    Ear Damage from a Small Firecracker

    Check the way you defined area for waves that propagate in space.
  14. M

    Sets & limit points and stuff

    The question says: Let A be a set and x a number. Show that x is a limit point of A if and only if there exists a sequence x_1 , x_2 , ... of distinct points in A that converge to x. Now I know from the if and only if statement that I need to prove this thing both ways. So, the...
  15. M

    How to prove stuff about linear algebra?

    Yes, that would make a bit more sense. Sometimes I understand what I mean to do, but don't know how to say it. :rolleyes: Thanks a bunch!
  16. M

    How to prove stuff about linear algebra?

    How to prove stuff about linear algebra? Question: Suppose (v_1, v_2, ..., v_n) is linearly independent in V and w\in V. Prove that if (v_1 +w, v_2 +w, ..., v_n +w) is linearly dependent, then w\in span(v_1, ...,v_n). To prove this I tried... If (v_1, v_2, ..., v_n) is linearly...
  17. M

    Do open sets stay open?

    Use the definition of an open set to show that if a finite number of points are removed, the remaining set is still open. Definition: A set is open if every point of the set lies in an open interval entirely contained in the set. I'm a bit lost, but I think that I somehow need to show...
  18. M

    Prove lim = inf(x)

    Question: Suppose there is a set E\subset \Re is bounded from below. Let x=inf(E) Prove there exists a sequence x_1, x_2,... \in E, such that x=lim(x_n). I am not sure but it seems like my x=lim(x_n) =liminf(x_n). In class we constructed a Cauchy sequence by bisection to find sup...
  19. M

    Compute sup,inf, and more

    So that would mean that my inf = -1, just like I thought it should be. :rolleyes: Thanks a lot!
  20. M

    Inequality of Supremums

    Ok, this is what I have for the equality part if I'm understanding you right. let sup(A)=sup(B) then sup(A\cap B)=sup(A) And the inequality would look like this? let sup(B)\leq sup(A) then sup(A\cap B)\leq sup(A) Is that right? It seems too simple...
  21. M

    Compute sup,inf, and more

    Question: (I've got a few like this, so I'd like to know if I am doing them correctly.) Compute the sup, inf, limsup, liminf, and all the limit points of the following sequence x_1, x_2,... where x_n = 1/n + (-1)^n What I did was write down the first few terms to get an idea of the...
  22. M

    Inequality of Supremums

    Theorem: For every non empty set E of real numbers that is bounded above there exists a unique real number sup(E) such that 1. sup(E) is an upper bound for E. 2. if y is an upper bound for E then y \geq sup(E). Prove: sup(A\cap B)\leq sup(A) I can show a special case of...
  23. M

    More Cauchy equivalence

    Question: Prove that if a Cauchy sequence x_1, x_2,... of rationals is modified by changing a finite number of terms, the result is an equivalent Cauchy sequence. All the math classes I have taken previously were computational, and my textbook contains almost no definitions. So, I...
  24. M

    Prove Cauchy sequence & find bounds on limit

    Here's the problem statement: Prove that x_1,x_2,x_3,... is a Cauchy sequence if it has the property that |x_k-x_{k-1}|<10^{-k} for all k=2,3,4,.... If x_1=2, what are the bounds on the limit of the sequence? Someone suggested that I use the triangle inequality as follows: let n=m+l...