# Posts by Z32

Total # Posts: 149

**Physics/Engineering**

1. The problem statement, all variables and given/known data I am using a Vishay strain indicator with it hooked up to a strain gage hooked up 1" away from the wall on the solid beam. The beam is .5" by .5", and it is solid. The beam is 16" long and I am ...

*November 17, 2011*

**Calculus**

yeah I forgot to type in the theta

*April 29, 2011*

**Calculus**

Express the region inside the leaf of the rose r=2sin2? in the first quadrant as an iterated integral over R?

*April 29, 2011*

**Calculus 3**

Compute the average value of following fuction over the region R? f(x,y)= sinxsiny R= { (x,y): 0 ≤ x ≤pi, 0 ≤ y ≤pi}

*April 15, 2011*

**Calculus**

A projectile is launched at an angle of 60 degrees to the horizontal from 6.5 ft above the ground at an initial speed of 150ft/sec. Assume the x-axis is horizontal, the positive y-axis is vertical (opposite g), the ground is horizontal, and only the gravitational force acts ...

*March 9, 2011*

**Calculus**

Find the domain of the following function h(x,y) = sqrt(x-9y+5)?

*March 9, 2011*

**Calculus**

Can two level curves of a function intersect; explain?

*March 4, 2011*

**Physics**

An electric power plant that would make use of the temperature gradient in the ocean has been proposed. The system is to operate between 20.0°C (surface water temperature) and 5.00°C (water temperature at a depth of about 1 km). The first question asks What is the ...

*February 26, 2011*

**Calculus**

Consider the parabola r(t)=<t-t^2>, does the principal unit normal vector point in the + or - y-direction along the curve?

*February 25, 2011*

**Calculus**

What does the arc length formula give for the length of the line r(t)=<t,t,t> for 0 ≤ t ≤ 1?

*February 22, 2011*

**Calculus 3**

Determine whether the lines intersect(have a common point) and if so, find the coordinates of that point? r(t) = < 4t+3, 4t + 2, 6t + 6>, for -infinity < t < infinity R(s) = < s + 2, 3s - 1, -4s + 10>, for -infinity < t < infinity And if r and R ...

*February 18, 2011*

**Physics**

I got lost when you got to: = Qout - Qout/3.85 = 0.7403 Qout What did you exactly do? I'm not seeing where those two Qout's came from and how you got the .7403.

*February 16, 2011*

**Physics**

How much energy does it extract from the outside air with coefficient of performance 3.85? A heat pump has a coefficient of performance of 3.85 and operates with a power consumption of 6.91 x 10^3 W. The first part of the question asked How much energy does it deliver into a ...

*February 16, 2011*

**Physics**

Thank you!

*February 16, 2011*

**Physics**

A freezer has a coefficient of performance of 6.30. It is advertised as using 486 kWh/yr. Note: One kilowatt-hour (kWh) is an amount of energy equal to running a 1-kW appliance for one hour. a) On average, how much energy does it use in a single day? I got 4.79 x 10^6 J (b) On...

*February 16, 2011*

**Physics**

If the stone strikes the ground 65 m away, find the time of flight and initial speed? Vxi = 17.7 m/s Vyi = 8.636 m/s xi = yi = 0, yf = -65.0 m, ay = -g, and vi = 19.7 m/s This is my work so far: trying to find t: 4.9t^2 - 8.636 -65=0 Then I used the quadratic formula and got t...

*September 9, 2010*

**Math**

Nevermind. You gotta use the quadratic formula.

*September 9, 2010*

**Math**

Solve for t. -45.0 m = (8.636 m/s)t + ½(-9.80 m/s^2)t^2 ?

*September 9, 2010*

**Physics**

(Vectors) If |A x B| = 6.45AB, what is the angle between A and B?

*September 3, 2010*

**Calculus**

Evaluate the integral from 2/sqrt2 to 4; 1/(t^3 sqrt(t^2-4))?

*September 3, 2010*

**Physics**

Would it be sqrt( (51.2)^2 + (18.7)^2 )?

*September 2, 2010*

**Physics**

A crow flies in two successive displacements to a point that is 80 m to the west. Its first displacement is 80 m in a direction θ = 50° west of north. What is the magnitude of its second displacement? What is its direction as measured by the angle θ measured west...

*September 2, 2010*

**Physics**

Junes Verne in 1865 suggested sending people to the Moon by firing a space capsule from a 195 m long cannon with a launch speed of 12.78 km/s. What would have been the unrealistically large acceleration experienced by the space travelers during launch? ____ m/s^2

*September 1, 2010*

**Physics**

One cubic meter (1.00 m^3) of aluminum has a mass of 2.70 multiplied by 10^3 kg, and the same volume of iron has a mass of 7.86 multiplied by 10^3 kg. Find the radius of a solid aluminum sphere that will balance a solid iron sphere of radius 1.40 cm on an equal-arm balance.

*August 27, 2010*

**Philosophy**

Does Bonnie Steinbock think committing adultery is okay or not okay?

*April 29, 2010*

**Calculus**

Estimate the area under the graph f(x)=3x^3 + 5 from x=-1 to x=5 using 12 mid points? I got the right answer for using 6 mid points but what mid points would I use for 12?

*April 20, 2010*

**Calculus**

Determine the y-coordinate of the critical point for the function where 0<x<5? I got the derivative which is -1/x^2 + 1/(5-x)^2 but I don't know how to get the answer. The answer is y=4/5 but I was wondering how do you get that?

*April 13, 2010*

**Calculus**

Suppose that f(x) = (5x + -2)^(1/2) Find an equation for the tangent line to the graph of f(x) at x=1. Tangent line: y=?

*February 16, 2010*

**Calculus**

What's the derivative of x^2(1- x/6)?

*February 9, 2010*

**Calculus**

Reflecting the graph calculus problem f(x) = 5^x? reflecting the graph about the x-axis and the y-axis: y=___________ reflecting the graph about the line y = 3. y=__________

*January 27, 2010*

**Calculus**

The velocity v(t)= -t^2 + 6t - 8, find the displacement and distance traveled during the time interval [-1,5]?

*December 11, 2009*

**Calculus**

Oh, okay. I got it.

*December 9, 2009*

**Calculus**

The parenthesis are in the wrong spot? I still can't figure it out.

*December 9, 2009*

**Calculus**

Evaluate the indefinite integral: x^2 / (3-4x^3)^6 I got -1/(60(4x^3-3))^5 but it's not right.

*December 9, 2009*

**Calculus**

Find the concavity and min and max for f(x) = x*sqrt(x^2+36) defined on the interval [-4, 7]?

*December 8, 2009*

**Calculus**

f(x) = 6e^(-5x) ln(x), find f'(3)?

*December 7, 2009*

**Calculus**

Nope.

*November 21, 2009*

**Calculus**

Derivative.

*November 21, 2009*

**Calculus**

[Integrals] h(x)= -4 to sin(x) (cos(t^5)+t)dt h'(x)=?

*November 21, 2009*

**Calculus**

That's supposed to be an integral sign.

*November 18, 2009*

**Calculus**

3 ⌠ 2⌡ (2x^2+5) / x^2 dx =? I got 1.66 but it was wrong.

*November 18, 2009*

**Calculus**

One quick question, for the "area=1/2 b H= 1/2 (12-3.5)(24-7)", how did you get the 24?

*November 15, 2009*

**Calculus**

I added the two areas up and got 84.5 which is the correct. Thanks!

*November 15, 2009*

**Calculus**

Evaluate the integral by interpreting it in terms of areas as 0 goes to 12 |2x - 7|dx? This is my work so far: 2x-7=0 x=7/2 slope = 2; y-int = (0, -7) Area of a triangle is 1/2BH.

*November 15, 2009*

**Calculus**

Find an overestimate and underestimate that the bug crawls during an hour v= 1 / [2+t]? For time, t, in hours, 0 <= t <= 1, a bug is crawling at a velocity, v, in meters/hours given by v = 1 / [2+t]. Use delta t = 0.2 to estimate the distance that the bug crawls during ...

*November 13, 2009*

**Calculus**

Estimate the area under the graph of f(x) = 2x^3 + 3 from x= -1 to x=5, first using 6 approximating rectangle and right endpoints, and then improving your estimate using 12 approximating rectangles and right endpoints. When using the left and right endpoints, is there a ...

*November 10, 2009*

**Calculus**

f(x) = [3/x^2] - [5/x^7], F(x) is the antiderivative of f(x) with F(1)=0. F(x) = ? I have no idea how to approach this problem. The fractions are scaring me.

*November 6, 2009*

**Calculus**

Oh dang. That's what I forgot. The x's. I put in the x's and the answer was correct. Thanks!

*November 5, 2009*

**Calculus**

What is the antiderivative of f(x)= 2x^8 + 10x^5 - 8x^4 - 4? I got (2/9)^9 + (10/6)^6 - (8/5)^5 - 4x but it's not right.

*November 5, 2009*

**Calculus**

A fence is to be built to enclose a rectangular area of 280 square feet. The fence along three sides is to be made of material that costs 6 dollars per foot, and the material for the fourth side costs 15 dollars per foot. Find the length L and width W (with W<= L) of the ...

*November 2, 2009*

**Calculus**

F(x) = x^3 / (x-16) is concave up and down on what intervals? I got the derivative to be f' = (x^4 - 48) / (x^2-16)^2 and I found the local min and max but now I need to find where it concaves up and down.

*October 27, 2009*

**Calculus**

What are the critical points of f(x)= e^x / 3+e^x?

*October 27, 2009*

**Calculus**

Oh, okay. I found out I had to use the quadratic formula. Thanks for the help!

*October 26, 2009*

**Calculus**

I got 0 for one of my inflections since a 0 in the place of the "x"(4x^2 + 9x - 36) would make it zero. But I'm not sure what would need to go into the other x's to make it 0. I tried 4/9 9/36 and 36/9 but I couldn't get it.

*October 26, 2009*

**Calculus**

Find the inflection points for f(x) = 12x^5 + 45x^4 - 360x^3 + 7

*October 26, 2009*

**Calculus**

Thanks.

*October 23, 2009*

**Calculus**

Help me simplify this down some more so I can set it to zero and find my critical points. f(x) = x^3 (x+2)^6 f'(x) = x^3 * 6(x+2)^5 + 3x^2 * (x+2)^6

*October 23, 2009*

**Caluclus**

Nevermind, I had an error in my calculations. It was sqrt(8128). I got the answer.

*October 23, 2009*

**Caluclus**

I redid my math and I think I did my calculations wrong. I got 8 +- sqrt(8000)/ -18 but it's still wrong.

*October 23, 2009*

**Caluclus**

[Mean Value Theorem] f(x)=-3x^3 - 4x^2 - 2x -3 on the closed interval [0,8]. Find the smallest value of c that satisfies the conclusion of the Mean Value Theorem for this function defined on the given interval. I got 8 - sqrt(5696) / -18 = 3.748436059 but it's not right.

*October 23, 2009*

**Calculus**

I tried that answer but it wasn't right. I tried sqrt 2 and it was right.

*October 22, 2009*

**Calculus**

What is the x coordinate of the absolute minimum of 6x + [12/x] when x > 0?

*October 22, 2009*

**Calculus**

What's the derivative of (x-1)(x-7)^3+10?

*October 20, 2009*

**Calculus**

What is the absolute max and absolute min of 3+13 |t-8| for -1 <= t <= 11? The absolute max of this function is ______ and occurs at ? The absolute min of this function is______ and occurs at?

*October 20, 2009*

**Calculus**

Can someone break this down for me step by step? I'm reviewing for a midterm and got stuck on this problem. 5xy - 3x - 4 = 0 y' at (2,1) I'm not sure where the 5 goes when you apply the product rule to the xy.

*October 15, 2009*

**Calculus**

What is the derivative of f(x)=5^x log6(x)?

*October 15, 2009*

**Calculus**

Find the derivative of 1/8tan^(-1)(x/8) & (x/2)(sqrt(64-x^2) + 32sin^(-1)(x/8)?

*October 14, 2009*

**Calculus**

Use linear approximation to estimate the amount of paint in cubic centimeters needed to apply a coat of paint 0.03 cm thick to a hemispherical dome with a diameter of 45.000 meters.

*October 13, 2009*

**Calculus**

Not correct.

*October 13, 2009*

**Calculus**

A 25 foot ladder is leaning on a 9 foot fence. The base of the ladder is being pulled away from the fence at the rate of 10 feet/minute. How fast is the top of the ladder approaching the ground when the base is 9 from the fence? [Note: The ladder is protruding over the top of ...

*October 13, 2009*

**Calculus**

Newton's Law of Cooling states that the rate at which an object cools is proportional to the difference in temperature between the object and the surrounding medium. Thus, if an object is taken from an oven at 303 F and left to cool in a room at 74 F, it's temperature ...

*October 13, 2009*

**Calculus**

Find the derivative of f(x)=x^2sinh^(-1)(3x)?

*October 13, 2009*

**Calculus**

Find the derivative of tanh(e^t)

*October 9, 2009*

**Engineering Materials**

Using mechanics of materials principles (ie. equations of mechanical equilibrium applied to a free-body diagram), derive the following equations. sigma' = sigma cos^2 θ = sigma(1+cos 2θ / 2) and tau = sigma sin θ cos θ = sigma( sin2θ / 2)

*October 8, 2009*

**Calculus**

[Inverse Functions] f(x)= 5cos(x)sin^(-1)(x) f'(x)=?

*October 7, 2009*

**Calculus**

The population of a region is growing exponentially. There were 40 million people in 1980 (when t=0) and 50 million people in 1990. Find an exponential model for the population (in millions of people) at any time t, in years after 1980. P(t)= Predicted population in the year ...

*October 6, 2009*

**Calculus**

[Exponential growth & decay] The half-life of radioactive strontium-90 is approximately 29 years. In 1965, radioactive strontium-90 was released into the atmosphere during testing of nuclear weapons, and was absorbed into people's bones. How many years does it take until ...

*October 6, 2009*

**Calculus**

The limit below represents the derivative of some function f at some number a. State such an f and a. lim x-->2 2^x-4/x-2 f(x)=_______ a=_______

*October 2, 2009*

**Calculus**

F(x)=5e^x - 10 / 24e^x + 12 f^(-1)(x)=? a=? b=?

*October 1, 2009*

**Calculus**

The expression e^x / e^(4+x) can be written as e^f(x), where f(x) is a function of x, find f(x)?

*September 29, 2009*

**Calculus**

Evaluate the following limits. lim as x approaches infinity 6/e^x + 7=____? lim as x approaches negative infinity 6/e^x+7=____?

*September 29, 2009*

**Calculus**

Nevermind, got it.

*September 28, 2009*

**Calculus**

So, m and b are?

*September 28, 2009*

**Calculus**

Use linear approximation, i.e. the tangent line, to approximate (the 3 is inside the v part if you know what I mean, it's not 3 times sqrt) 3√125.2 as follows: Let f(x) = 3√x. The equation of the tangent line to f(x) at x=125 can be written in the form y=mx+b ...

*September 28, 2009*

**Calculus**

I typed in 5.01999999999 and it took it. Weird.

*September 27, 2009*

**Calculus**

Find the linearization of f(x)= sqrtx at x=25 and use the linearization to approximate sqrt25.2 This is my math: 5+ 1/10 * (25.2-25) but it's wrong.

*September 27, 2009*

**Calculus**

Oh I'm missing the last ^2 at the end. Thanks!

*September 27, 2009*

**Calculus**

[Linear Approximations and Differentials] I tripled checked my work but I'm still not getting the correct answer. y=3x^2 x=3 & delta x =0.2 I get 3(3.2)^2 - 3(3) = 21.72

*September 27, 2009*

**Calculus**

What the heck? haha. I was going crazy could I could've swore I did my calculations right. Oh well, thanks for the help man. I appreciate it.

*September 25, 2009*

**Calculus**

Water is being pumped into an inverted conical tank at a constant rate. The tank has height 9 meters and the diameter at the top is 4 meters. If the water level is rising at a rate of 28 centimeters per minute when the height of the water is 3.5 meters, find the rate at which ...

*September 25, 2009*

**Calculus**

Hmm. Stupid online hw wants it perfectly I guess. Thanks though.

*September 25, 2009*

**Calculus**

At noon, ship A is 10 nautical miles due west of ship B. Ship A is sailing west at 16 knots and ship B is sailing north at 24 knots. How fast (in knots) is the distance between the ships changing at 3 PM? This is what I got but it's not right 28.727

*September 25, 2009*

**Calculus**

Ahh, there we go. Can't believe such a little number could cause it to be wrong. Thanks.

*September 25, 2009*

**Calculus**

Not right for some reason.

*September 25, 2009*

**Calculus**

A plane flying with a constant speed of 5 km/min passes over a ground radar station at an altitude of 4 km and climbs at an angle of 35 degrees. At what rate, in km/min is the distance from the plane to the radar station increasing 10 minutes later? I got it down to [250-20cos...

*September 25, 2009*

**Calculus**

Got it down to 3.157 which is correct. Thanks!

*September 24, 2009*

**Calculus**

Air is being pumped into a spherical balloon so that its volume increases at a rate of 30 cubic centimeters per second. How fast is the surface area of the balloon increasing when its radius is 19 cm? V= 4/3*pi*r^3 S= 4 pi r^2

*September 24, 2009*

**Calculus**

Hmm. I tried that and it wasn't correct.

*September 24, 2009*

**Calculus**

A spherical snowball is melting in such a way that its diameter is decreasing at rate of 0.2 cm/min. At what rate is the volume of the snowball decreasing when the diameter is 16 cm.

*September 24, 2009*

**Calculus**

Oh my bad. I meant dy/dt. I understand now. Thanks!

*September 24, 2009*