11/17/13
What is its resulting acceleration?
Two 5 kg masses are attached to opposite ends of a long massless cord which passes tautly over a massless frictionless pulley. The upper mass is initially held at rest on a table 50 cm from the...
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11/16/13
What's the downward acceleration?
Two masses are connected by a light cord which is looped over a light frictionless pulley. If one mass is 3.0 kg and the second mass is 5.0 kg, what's the downward acceleration of the heavier mass?...
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11/16/13
What's the tension?
Two masses 5.0 and 7.0 kg are originally at rest on a frictionless surface. The masses are connected by a light cord. A second cord is attached to the 7.0 kg mass and pulled with a horizontal force...
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11/13/13
Compute A^2 and A^3.
Compute A^2 and A^3. Make a prediction for A^5 and A^n:
A=[1, b, 0, 1] and A=[2, 2, 0, 0].
The first row: 1, b.
The second row: 0, 1.
The first row: 2, 2.
The second row: 0, 0.
11/12/13
What are those matrices?
This 4 by 4 matrix will need elimination matrices E21 and E32 and E43. What are those matrices?
A=[2, -1, 0, 0, -1, 2, -1, 0, 0, -1, 2, -1, 0, 0, -1, 2].
The first row is 2, -1, 0, 0.
The...
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11/12/13
Find and solve?
The parabola y=a+bx+cx^2 goes through the points (x, y)=(1, 4) and (2, 8) and (3, 14). Find and solve a matrix equation for the unknowns (a, b, c).
a+b+c=4
a+2b+4c=8
a+3b+9c=14
a=2, b=1,...
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11/10/13
What is the magnitude?
A 20 kg box remains at rest on a horizontal surface while a person pushes directly to the right on the box with a force of 60 N. The coefficient of kinetic friction between the box and the surface...
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11/09/13
What's the net force?
A person pushes a block of mass M=6.0 kg with a constant speed of 5.0 m/s straight up a flat surface inclined 30 degrees above the horizontal. The coefficient of kinetic friction between the block...
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11/09/13
What is the coefficient of kinetic friction?
A 22 kg suitcase is dragged in a straight line at a constant speed of 1.10 m/s across a level airport floor by a student on the way to Mexico. The individual pulls with a 1.0x10^2 N force along a...
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11/09/13
What is the force?
A spaceman of mass 80 kg is sitting in a spacecraft near the surface of the Earth. The spacecraft is accelerating upward at five times the acceleration due to gravity. What is the force of the...
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11/07/13
Find and solve a matrix equation?
The parabola y=a+bx+cx^2 goes through the points (x, y)=(1, 4) and (2, 8) and (3, 14). Find and solve a matrix equation for the unknowns (a, b, c).
What 3 by 3 matrix E?
What 3 by 3 matrix E multiplies (x, y, z) to give (x, y, z+x)?
11/06/13
Find the matrix P?
Find the matrix P that multiplies (x, y, z) to give (y, z, x). Find the matrix Q that multiplies (y, z, x) to bring back (x, y, z).
10/28/13
Find a combination?
Find a combination x1w1+x2w2+x3w3 that gives the zero vector: w1=[1, 2, 3], w2=[4, 5, 6], w3=[7, 8, 9].
The answer is (1/2)w1-w2+(1/2)w3.
10/26/13
Find four perpendicular unit vectors?
Find four perpendicular unit vectors with all components equal to 1/2 or -1/2.
10/26/13
What is that least?
An overhead view of a 12 kg tire that is to be pulled by three horizontal ropes. One rope's force (F1=50 N) is indicated. The forces from the other ropes are to be oriented such that the tire's...
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10/25/13
How could you prove?
How could you prove cube root of (xyz)≤(1/3)(x+y+z)(geometric mean≤arithmetic mean)?
10/25/13
What are the smallest and largest values?
If llvll=5 and llwll=3, what are the smallest and largest values of llv-wll? What are the smallest and largest values of v*w?
10/22/13
Find two vectors?
Find two vectors v and w that are perpendicular to (1, 0, 1) and to each other.
10/22/13
Find the angle?
Find the angle θ (from its cosine) between v=[2, 2, -1] and w=[2, -1, 2].
These are vectors with 2 on top, 2 on middle, -1 on bottom. And w with 2 on top, -1 on middle, 2 on bottom. I got the...
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