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kenneth collins

kenneth c.

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A block with mass m = 5.0 kg collides with an unstretched horizontal Hookean spring and compresses the spring 11.4 cm before stopping. The coefficient of friction between the block and the horizontal surface is $\mu_k$ = 0.3. The speed of the block when it first contacts the spring is 1.5 m/s. 1. Draw a force diagram for the block after contact with the spring but before it stops. 2. Calculate the work done by the force of friction on the block from the point of contact with the spring to the point where it stops. $W = Fd$ $W = 15(0.114)$ $F = \mu_k N$ $\sum F = 0$ $mg = N$ $N = 50 N$ $F = 15 N$ $W = 1.71 J$ 3. Calculate the work done by the spring force over the same displacement in terms of the spring constant $k$. $F_s = -kx$ $\Delta W = \Delta K$ $W_s + W_f = 0 - \frac{1}{2}(5)(1.5)^2$ $W_s + 1.71 = -5.625$ $W_s = \frac{1}{2}kx^2$ $W_s = \frac{1}{2}k(0.114)^2$ $W_s \approx -7.34 J$ $(W_s = -176.625)$ 4. Find the spring constant. $64.98k = 176.625$ $k = 2.718$ 5. Suppose the coefficient of static friction $\mu_s$ = 0.4. Does the block remain stopped or does it begin moving to the left? Justify your answer (because...). The block would remain stopped as friction always has $-W_f$. friction would go against the $W_s$ as soon as it tried using any force to move the opposite way. Compare forces!

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\begin{cases} x + 3y - 2z = 0 \\ 2x + 4z = 2 \\ 4x + 6y = 2 \end{cases}

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Two firms (A and B) have marginal cost MC_A and MC_B.

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Any alteration in the DNA sequence of a gene that alters the amino acid sequence but not the size of the encoded polypeptide is defined as a(n) ____________ mutation. Question 2 options: nonsense frameshift silent neutral missense NONE of these terms accurately completes this sentence

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8. Simple proofs. Give short and complete proofs of the following statements. Present your answers in an organized way. In each case assume A is a square matrix. (a) If A is invertible, then $det(A^{-1}) = \frac{1}{det(A)}$ (b) If B and C are both inverses of A, then in fact B = C. (c) If A has eigenvalue $\lambda$ and corresponding unit eigenvector $\vec{x}$, then $A\vec{x} = \lambda\vec{x}$.

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Problem 1 - Design an account class with the following member variables: o Account number o Account balance - Define proper member variables and functions for this class. - Overload the operator == to check whether two accounts are equal or not. Two accounts are equal. If the account number is the same.

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You collect data on unemployment percentages and minimum wages for 500 random cities in the U.S. in 2015, and then you estimate the following OLS regression: Unemployment_i=2.3+0.4Minimum Wage_i where unemployment percentages range from 4%-20% and minimum wages range from $0-$25 per hour across cities in your sample. Your estimation results show that SE(beta0hat)=0.9 and SE(beta1hat)=0.13. Consider the results from the sample regression function to answer the following question: As a city's minimum wage increases by $1 per hour, unemployment ... B) Now you want to test the two-sided hypothesis that beta0=1 using alpha=0.05. What is the p-value associated with this test? Round your answer to two decimal places. Based on your answer to question 7, you reject the null hypothesis. C) Test the \"less-than\" one-sided hypothesis that beta1=0.5 using alpha=0.05. What is the p-value associated with this test? Round your answer to two decimal places. D) Construct a 99% confidence interval for beta1. What is the lower bound of this confidence interval? Round your answer to two decimal places E) Construct a 99% confidence interval for beta1. What is the upper bound of this confidence interval? Round your answer to two decimal places.

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2 Find R such that I = 5A 10\Omega I R 45A 40\Omega 20\Omega 30\Omega

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Demonstrate the divergence theorem for the vector field below, using a cube of side L with a corner at the origin of the coordinate system and edges lying along the positive x, y and z axes. (In other words, demonstrate that the divergence of the vector field integrated over the volume of the cube equals to the total flux of the vector field over the surface of the cube.) \vec{A} = y\hat{y} Calculate the line integral for the vector field using two different paths in the xy plane: a) from point (0,0) to point (1,0) to point (1,1) b) from point (0,0) to point (0,1) to point (1,1) Compare these results.

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Rob Lucas is very optimistic about the profitability of Wal-Mart Corp. such that he invested in 10,000 shares at the end of the day. The current market price of a share of common stock of Wal-Mart is $100. The conditions are 50% of initial margin and a maintenance (minimum) margin of 30%. Surprisingly, the next day, at the opening of the market, the price decreases to $90. a) Rob's equity position before and after the price decrease b) The rate of return on his position c) Would he receive a margin call? Determine the price at which Rob would receive a margin call.

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