Recent content by alejandro7

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    Force and momentum in gymnastics position

    Is my result for R correct or should I include the other arm in the calculation (so the forces would be 2 x W/2, 2 x Warm, 2 x R and W)?
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    Force and momentum in gymnastics position

    The torque that the man has to generate about is shoulder to stop his arms rotating is the reaction force (R) times the distance. But which distance?
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    Force and momentum in gymnastics position

    Hi. I'm trying to solve this problem but I'm not sure my solution is right: "Suppose that a male gymnast wishes to execute an iron cross during a gymnastics session. The total mass of the gymnast is 60 kg. Each ring supports half of the gymnast's weight. Assume that the weight of one of his...
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    Graduate Show that the set of sets {An} has n elements

    We define by recursion the set of sets {An:n∈ℕ} this way: A_0=∅ A_n+1=A_n ∪ {A_n}. I want to prove by induction that for all n∈ℕ, the set A_n has n elements and that A_n is transitive (i.e. if x∈y∈A_n, then x∈A_n). My thoughts: for n=0, A_1 = ∅∪ {∅} = {∅} then, for n+1: A_n+2...
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    Equations of movement of partical that slides inside a container

    It = using spherical coordinates. I will try that.
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    Equations of movement of partical that slides inside a container

    Oh, my bad. Yes, but is it necessary? What is the best path to follow?
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    Equations of movement of partical that slides inside a container

    No, there is not optimization involved in the problem. I'm familiar with the pendulum but the relation between vectors (with vector calculus notation) and forces is confusing me.
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    Equations of movement of partical that slides inside a container

    Hello I'm trying to solve the following problem: "Find the equations of movement of a particle of mass m that slides on the inner surface of a spherical container given by the equation x^2 +y^2 + z^2 = 1, z≤0" I know I have to use F=ma and I've tried derivating the equation but I...
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    Prove involving parabolic mirrors

    I'm having trouble with the following problem: "Consider the parabolic mirror given by the equation $z=x^2+y^2$. Show that when the rays of light that travel parallel to the $z$ axis pass through the same point when reflected." I'm familiar with the law of reflection but I'm stuck...
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    Undergrad Maximum size of a set containing logical expressions

    Hi Can you please help me with this problem? "What is the maximum size of a set A of logical expressions that only use →, p, q : each pair of elements of A are not equivalent?" I've found 6 different possible truth values. Is this the maximum size? If yes, how do I prove it? Thanks!
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    Solving ∞^0 Indetermination: L'Hospital's Rule Help Needed

    Ok I have: e^lim when x-> of ((ln(1-2^x)/x)) L'Hôpital now?
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    Solving ∞^0 Indetermination: L'Hospital's Rule Help Needed

    1/x goes down.
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    Solving ∞^0 Indetermination: L'Hospital's Rule Help Needed

    Hi, I'm having troubles wiith this problem: limit when x->∞ (1+2^x)^(1/x) I don't know how to proceed (I know I have to use l'Hospital's rule). It's a ∞^0 indetermination. Thanks!