Recent content by Millacol88

  1. M

    Central Limiting Theorem?

    Homework Statement The amounts of time that a cashier spends processing individual customers' orders are independent random variables with mean 2.5 minutes and standard deviation 2 minutes. a) What is the approximate probability that it will take more than 4 hours to process orders of 100...
  2. M

    Poisson, Binomial Distributions

    Homework Statement The number of claims that an insurance company receives per week is a random variable with the Poisson distribution with parameter λ. The probability that a claim will be accepted as genuine is p, and is independent of other claims. a) What is the probability that no claim...
  3. M

    Is momentum conserved in y direction ?

    Is it? If the ball is in your system then you must account for the upward force F applied on it.
  4. M

    Is momentum conserved in y direction ?

    The gravitational force and normal force from the earth do not cancel out though. There is a reaction force from the Earth equal in magnitude to the force applied to the ball by the man. This force is not cancelled out by the force of the cart pushing on the Earth because the Earth is not in...
  5. M

    Is momentum conserved in y direction ?

    Say that you take the Ball, Man, Cart system. The forces between the ball and the man, and the man and the cart are all action-reaction pairs and thus cancel out. But the cart also pushes on something outside of the system: the Earth. The Earth pushes back with a reaction force. Is this force...
  6. M

    The end of a ski jump(projectile motion)

    Perhaps I'm misunderstanding the question, but if a skier goes off a jump with a known velocity, then their path through space is determined. Isn't it clear that he can only land in one particular spot on the ramp?
  7. M

    Efficiency of a Lightbulb

    I think it's safe to assume that the useful energy in this case is the light being emitted from the bulb. Which would mean that 51 J of light energy is emitted. The other energy doesn't "remain in the circuit" it is lost to heat.
  8. M

    Grade 11 Physics Problem - Vectors and Water Currents

    Not quite. The horizontal part of the triangle is her resultant velocity,or the vector sum of her speed with respect to the water and the current flow with respect to the shore. Her velocity relative to the water should be inclined at some angle with the horizontal, making it the hypotenuse of...
  9. M

    Grade 11 Physics Problem - Vectors and Water Currents

    This is correct. I think you may be overthinking this. If she ends up 15.36 m downstream, that's how far she will have to walk to reach the market. Your intuition is right and you are correct that this is basically a trigonometry problem. Knowing that her speed relative to the water is 2.5...
  10. M

    Linear Algebra: Spans and Dimensions

    Ok, so assuming we reduce the set in U to a basis: then if v is in U the given generating set for W is linearly dependent. Then v would be removed from this set, making it linearly independent. This implies that U and V share a basis, and thus their dimensions are the same. If v is not in U...
  11. M

    Linear Algebra: Spans and Dimensions

    Okay, so if I reduced the generating set for U to a basis, I would know its linearly independent, but then where would I go with it?
  12. M

    Linear Algebra: Spans and Dimensions

    Homework Statement Given v1, v2 ... vk and v, let U = span {v1, v2 ... vk} and W = span {v1, v2 ... vk, v}. Show that either dim W = dim U or dim W = 1 + dim U. The Attempt at a Solution I'm not really sure where to start. If I knew that {v1, v2 ... vk} was linearly independent, then it would...
  13. M

    Linear Algebra: Linear indepency of a set of Polynomials

    Thanks for the reply! Today I was able to prove (1) by contraposition but I thought that meant I had to prove (2) by contraposition as well. Can I just prove the positive statement for (2)? Edit: Wait, taking statement A as {p, q, pq} is linearly independent and statement B as deg p ≥ 1 and deg...
  14. M

    Linear Algebra: Linear indepency of a set of Polynomials

    Homework Statement Let {p, q} be linearly independent polynomials. Show that {p, q, pq} is linearly independent if and only if deg p ≥ 1 and deg q ≥ 1. Homework Equations λ1p + λ2q = 0 ⇔ λ1 = λ2 = 0 The Attempt at a Solution λ1p + λ2q + λ3pq = 0 I know if λ3 = 0, then the coefficients of...
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