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Quiz 11; Problems 1, 16, 29, 30, 37, 38, 41, 42, 46, 47, 51, 52, 55, 56

TURN IN: 1, 16, 30, 38, 42, 46, 52

error log #1: 12/18/2010 08:36:41 PM errors to 16, 38 and 42 are corrected.

1. If a particle starts at a maximum horizontal displacement (at x = A) from the origin ( x= 0), after one cycle it has returned to its original location (y = A.). When it begins to move it travels left and reaches the origin after a distance equal to A, the amplitude. It then travels a distance A to reach the minimum horizontal displacement ( x = -A.) before turning around. Think this through and compute the total distance, an even multiple of A. .

16.
(a) A is the coefficient in front to the expression.
(b) Assume pi = 3.14; thus 2*pi = 6.28. We have 6.28f = 6.40.
(c) Total energy = spring potential energy when x = A or x = -A. This potential energy is (1/2)*k*A². BUT you do not know the spring constant k. But you can find it. Use the formula for the frequency f, equation 11-7b. You know the mass m , so find k, then find the total energy.
(d) Total energy ( from part c) = KE + (spring PE) at any other time. In general, spring PE = (1/2)kx². Find KE for the given value of x. Use the value of k computed in the previous part.

30. Use equation 11-11a. Set the period equal to 0.80 seconds and solve for L by squaring both sides of the
equation. After that, re-compute the period using the same formula with the computed value of L and the new gravitational constant 0.37*g.

38.
(a) wavelength = v/f , where v = c = 3x10 ⁸ m/s. Find the two wavelengths.
(b) Compute two new wavelengths.

42.
(a) distance = 2*length = speed*time.
(b) Use equation 11-13. Here's the trick: You have to find m/L = mass /length. Well, L is given and mass m is found by multiplying the volume and density, where
volume = (area of circular cross-section of wire)*L and density = 7800 kg/m³ . Set the speed from part (a) equal to the right hand side of equation 11-13. Solve for the tension symbolized by F_T by squaring both sides of the equation.

46.
(a) Use equation 11-16 c.
(b) Take the square root of the right hand side of equation 11-16c.

52. See class notes and section 11-13.

error log #1: 12/18/2010 08:36:41 PM errors to 16, 38 and 42 are corrected.