Wednesday

September 3, 2014

September 3, 2014

Total # Posts: 500

**physics**

Two blocks are connected by a lightweight, flexible cord that passes over a frictionless pulley. If m1 = 3.8 kg and m2 = 9.2 kg, and block 2 is initially at rest 140 cm above the floor, how long does it take block 2 to reach the floor?
*September 23, 2012*

**Calc 3**

thank you!!!!!!
*September 22, 2012*

**Calc 3**

Use the Chain Rule to find ∂z/∂s and ∂z/∂t. z = tan(u/v), u = 7s + 4t, v = 4s − 7t
*September 22, 2012*

**Calc 3**

we were not given f(x,y) the whole problem is listed above, apparently there is a link that is supposed to help us but I followed it and don't know what I am doing wrong and I cannot post the link because it is on a special homework website.
*September 22, 2012*

**Calc 3**

If z = f(x, y), where x = r^2 + s^2 and y = 8rs, find ∂^2z/(∂r ∂s).
*September 22, 2012*

**calc 3**

yes i already got parts a and b i do not know how to do part c sorry i should have specified that in my post
*September 21, 2012*

**calc 3**

The length script l, width w, and height h of a box change with time. At a certain instant the dimensions are script l = 7 m and w = h = 5 m, and script l and w are increasing at a rate of 6 m/s while h is decreasing at a rate of 4 m/s. At that instant find the rates at which ...
*September 21, 2012*

**English**

1.I started play the oboe because [I've heard] it was a challenging instrument (a) no change (b) I'd have heard (c)I've been hearing (d) I'd heard 2. That was [four years ago and, I've] enjoyed learning to play (f) no change (g) four years ago, and I've...
*September 20, 2012*

**physics**

A crate of potatoes of mass 13.0 kg is on a ramp with angle of incline 30° to the horizontal. The coefficients of friction are μs = 0.76 and μk = 0.35. Find the frictional force (magnitude and direction) on the crate if the crate is sliding up the ramp.
*September 20, 2012*

**calc 3**

Use the Chain Rule to find dw/dt. w = ln (x^2 + y^2 + z^2)^.5 , x = 9 sin t, y = 6 cos t, z = 7 tan t
*September 20, 2012*

**Calc 3**

Find all partial derivatives? v = (xy)/(x-y) vxx= vxy= vyx= vyy=
*September 20, 2012*

**physics**

A barge is hauled along a straight-line section of canal by two horses harnessed to tow ropes and walking along the tow paths on either side of the canal. Each horse pulls with a force of 540 N at an angle of 12° with the centerline of the canal. What is the net force on ...
*September 19, 2012*

**calc 3**

Find all partial derivatives? v = (xy)/(x-y) vxx= vxy= vyx= vyy=
*September 19, 2012*

**calc 3**

Use polar coordinates to find the limit. [If (r, θ) are polar coordinates of the point (x, y) with r ≥ 0, note that r → 0+ as (x, y) → (0, 0).] (If an answer does not exist, enter DNE.) lim (x, y)→(0, 0) [(3e^−x^2− y^2) − 3]/ (x^2...
*September 17, 2012*

**Calc 3**

but there is no lHospitals rule in multivariable
*September 14, 2012*

**Calc 3**

Find the limit, if it exists. (If an answer does not exist, enter DNE.) lim (x, y)→(0, 0) of (x^2 + y^2)/[((x^2 + y^2 +64)^.5)-8]
*September 14, 2012*

**Calc 3**

A cooling tower for a nuclear reactor is to be constructed in the shape of a hyperboloid of one sheet. The diameter at the base is 300 m and the minimum diameter, 500 m above the base, is 200 m. Find an equation describing the shape of the tower in the coordinates where the ...
*September 12, 2012*

**Chemistry**

1.42 g/cm^2 to mg/mm^2
*September 4, 2012*

**calc 3**

The magnitude of a velocity vector is called speed. Suppose that a wind is blowing from the direction N45°W at a speed of 40 km/h. (This means that the direction from which the wind blows is 45° west of the northerly direction.) A pilot is steering a plane in the ...
*August 31, 2012*

**calc 3**

Question Find an equation of the set of all points equidistant from the points A(−2, 5, 2) and B(5, 1, −3).
*August 30, 2012*

**calculus**

hi i think i know what you mean already. my answer for F"(v) (-150v^5/2 + 40500v)/v^4 i simplified further, it became (-150v(v^3/2 - 270))/v^4 cancel off the common factor v it became (-150(v^3/2 - 270))/v^3 Am i correct??
*August 13, 2012*

**calculus**

based on my question, i retyped... F(v) : (600v^3/2 + 20250)/v F'(v) : (300v^3/2 - 20250)/v^2 F"(v) : (-150v^5/2 + 40500)/v^3 Reiny, isn't your answer suppose to be f(x) = 600 v^(3/2) + 20250 v^-1, instead of f(x) = 600 v^(1/2) + 20250 v^-1 ?? 1/2 power and 3/2 ...
*August 13, 2012*

**calculus**

I do not want the simplified answer by the way...I need the answer as an expression only
*August 13, 2012*

**calculus**

Ok but the power 5/2 is wrong? Should have been power 3/2? I keep on getting the answer 5/2.. I don't know which part of my working is wrong
*August 13, 2012*

**calculus**

Just want to check whether my answer is correct for quotient rule F(v) : (600^3/2 + 20250)/v F'(v) : (300^3/2 - 20250)/v^2 F"(v) : (-150v^5/2 + 40500)/v^3 Can anyone let me know whether my answer is correct for first and second derivative based on F(v) ??
*August 13, 2012*

**calculus**

yes it should be, F(v) : (600^3/2 + 20250)/v F'(v) : (300^3/2 - 20250)/v^2 F"(v) : (-150v^5/2 + 40500)/v^3 for F"(v), this is how i get: F'(v) : (300^3/2 - 20250)/v^2 F"(v) : ((300v^3/2 - 20250)' * v^2) - ((300v^3/2 - 20250) * (v^2)')/v^4 F"...
*August 13, 2012*

**calculus**

nope, it's not a typo. the 5/2 is the power of 5 over 2. it is not 5 divide by 2. is my above answer correct?
*August 13, 2012*

**calculus**

Just want to check whether my answer is correct for quotient rule F(x) : (600^3/2 + 20250)/v F'(x) : (300^3/2 - 20250)/v^2 F"(x) : (-150v^5/2 + 40500)/v^3 Can anyone let me know whether my answer is correct for first and second derivative based on F(x) ?? Thank you!!
*August 13, 2012*

**calculus**

A ship uses $( 7v^2 ) of fuel per hour when travelling at a constant speed of v km/h. Other expenses in operating the ship (i.e. crew and equipment) amount to $345 per hour. The ship makes a journey of 100 km. C(v) : (700v^2 + 34500)/v C'(v): (700v^2 - 34500)/v^2 C"(v...
*August 13, 2012*

**calculus**

i got the answer!! thank you!!!
*August 13, 2012*

**calculus**

pls ignore the above question... to make it clearer for the question, it is... f(x): (700v^2 + 34500)/v f'(x) : (700v^2 -34500)/v^2 f''(x) : ???
*August 13, 2012*

**calculus**

The question should be: f(x): 700v^2 + 34500/v f'(x) : 700v^2 -34500/v^2 f''(x) : ???
*August 13, 2012*

**calculus**

sorry typo error above, question is, f(x): 700v^2 + 34500/v f'(x) : 700v^2 -34500/v^2 f"'(x) : ???
*August 13, 2012*

**calculus**

how to find the second derivative of quotient rule? f(x): 700v^2 + 3450/v f'(x) : 700v^2 -3450/v^2 f"'(x) : ???
*August 13, 2012*

**calculus**

The 5 question is asking how many km/h...appreciated if anyone cld help...thank you!!
*August 12, 2012*

**calculus**

Hi i need help in this. Some of the parts i got the answer but some i don't. please help! A ship uses $(7v^2) of fuel per hour when travelling at a constant speed of v km/h. Other expenses in operating the ship (i.e. crew and equipment) amount to $345 per hour. The ship ...
*August 12, 2012*

**calculus**

i get the answer already! thank you!
*August 11, 2012*

**calculus**

Hi thanks for helping. But when differentiate pi^2 isn't that is 2pi? How come your answer is 2pi^2? and when different r^2 isn't that is 2r? How come your equation is dv/dt = 2pi^2 D r + 8/3*pi*r^2? Because my answer is 2pi D 2r + 8/3*pi*r*^2. anyone can explain? Thanks!
*August 11, 2012*

**calculus**

A bicycle wheel has a diameter D = 60 cm and the tyre has a cross sectional radius of r = 2.5 cm. The volume V of the inner tube is given by V = pi^2 D r^2 + (8/3*pi*r^3) If air is being pumped into the tyre so that the volume of the inner tube is increasing at the rate of 12 ...
*August 11, 2012*

**math**

In a time-use study, 20 randomly selected managers were found to spend a mean of 2.40 hours each day on paperwork. The standard deviation of the 20 scores is 1.30 hours. Also, the sample data appear to have a bell-shaped distribution. Construct the 95% confidence interval for ...
*July 29, 2012*

**statistics**

One of the problems with a study such as this one is the small size of the samples. If you wanted to estimate the proportion of a certain color of candy to within 2% of the actual proportion, how many individual pieces of candy must you sample? Assume you want to be 90% ...
*July 23, 2012*

**LIT 210**

What do you think Oedipus Rex and A Raisin in the Sun imply about Sophocles’ and Lorraine Hansberry’s cultural identities?
*July 20, 2012*

**Math**

thank you!!
*June 30, 2012*

**Math**

Im working on a math question and the answer is 2hr and 24min. I am getting 2.4 with my calculations how do i take 2.4 and get 2hr and 24min.???
*June 30, 2012*

**Algebra**

Thank you been 8 years and trying to go back to school trying to re learn and or remember thanks a bunch!!!!
*June 28, 2012*

**Algebra**

If two planes leave the same airport at 1:00 PM, how many miles apart will they be at 3:00 PM if one travels directly north at 150 mph and the other travels directly west at 200 mph? I understand that d = sqrt[300^2 + 400^2] d = sqrt[250,000] But im not sure how you get 500 ...
*June 28, 2012*

**Finance**

Carnation needs to buy a $12,500 part the part company is offering cash discount terms of 4/10, n30. Carnation has a tight cash flow, wants to discount a 180 day note dated February 12 with a maturity value of $10,300. Bank offers a discount rate of 6%. Should carnation ...
*June 6, 2012*

**Physics**

Two spherical objects with a mass of 7.60 kg each are placed at a distance of 2.93 m apart. How many electrons need to leave each object so that the net force between them becomes zero?
*June 6, 2012*

**physics**

Two small pith balls, each of mass m = 16.6 g, are suspended from the ceiling of the physics lab by 1.8 m long fine strings and are not moving. If the angle which each string makes with the vertical is è = 19°, and the charges on the two balls are equal, what is the...
*June 6, 2012*

**math**

pam is offered a salary of 28,000 a year for 30 years with annual raises of 6 % what would be pam's salary during her 5th year on the job
*April 26, 2012*

**Math**

The weights of adult long-tongued fruit bats are known to be normally distributed with a mean of 20.22 grams and a standard deviation of 3.23 grams. What is the probability that a randomly selected bat will: a) weigh at most 15 grams? b) weigh less than 30 grams?
*March 23, 2012*

**math**

The weights of adult long-tongued fruit bats are known to be normally distributed with a mean of 20.22 grams and a standard deviation of 3.23 grams. What is the probability that a randomly selected bat will: a) weigh at most 15 grams? b) weigh less than 30 grams?
*March 21, 2012*

**Physics**

wow I thought this was a homework help site. Not a be rude to someone you don't even know site? I have read the book thanks but physics is a hard topic to understand. You wasted your own time by commenting that rude comment. Thanks bye x
*March 21, 2012*

**Physics**

Tim and Ray have the same mass and they both climb up the same hill. Tim climbs the hill in 12 minutes and Ray in 22 minutes. a) Who does more work? b) Who develops the most power?
*March 21, 2012*

**Physics**

A blue whale materializes 11.5 km above an airless planet with an acceleration of gravity of 6.85 m/s2. What is the speed of the whale right before impact? (Work-Energy Theorem)
*March 21, 2012*

**Physics**

A car is driven at a constant speed of 85 km/h down a road. The car's engine delivers 49.2 kW of power. Calculate the average force that is resisting the motion of the car.
*March 21, 2012*

**Physics**

Michelle pulls a 14.5 kg wheeled cart with a rope along a flat road. The rope makes a 28.0 degree angle with the horizontal. If the tension in the rope is 350 N and she pulls the cart 56.7m how much work does Michelle do?
*March 21, 2012*

**Physics**

Bryant is fired from a cannon with an initial speed of 14 m/s. If his mass is 80 kg what is his initial kinetic energy?
*March 21, 2012*

**Physics**

A ball is moving at 82 m/s when it hits a ball at rest which has a mass fours times as big as its own. The formally stationary ball leaves the collision with a speed of 7.5 m/s what is the final velocity of the first ball?
*March 21, 2012*

**physics**

Neona is on a tricycle A, combined mass 62 kg, and Alyssia is on tricycle B, combined mass 54 kg. They are initially at rest, but they push off of each other. What is Neona's speed immediately after the push if Alyssia's is 4.2 m/s?
*March 21, 2012*

**Physics**

Kenya finally loses her cool and punches her teacher. The teacher weighs 85 kg. He sees the punch coming and begins to back up at a speed of 0.60 m/s. After Kenya clocks him, he is moving backwards at a speed of 0.82 m/s. If the contact time of Kenya's fist to the teachers...
*March 21, 2012*

**Physics**

Two trucks that appear to be identical collide on an icy road. One was originally at rest. The trucks stick together and move off at more than half the original speed of the moving truck. What can you conclude about the contents of the two trucks?
*March 21, 2012*

**Physics**

You are sitting at a baseball game when a foul ball comes in your direction. You prepare to catch it barehanded. In order to catch it safely, should you move your hands toward the ball, hold them still, or move them in the same direction as the moving ball? Explain.
*March 21, 2012*

**Physics**

As you lift a chair to store is upside down on a desk, gravity exerts a force, mg, downward and you exert a force of the same magnitude upwards. The two forces are equal in magnitude and opposite in direction. From this is would appear that no work was done, but you know you ...
*March 21, 2012*

**Physics**

Roads seldom go straight up a mountain, they wind back and forth. Explain why this is useful
*March 21, 2012*

**math**

6+10+6+7+6=35
*March 7, 2012*

**math**

i have 3 numbers 10,7,and 6 and need to make them work in 35...but it cant be like 7 into 35 it has to be all 3 numbers and can be used more than once but after another number like 10 + 7 +10 ect
*March 7, 2012*

**Math**

circumference (the crust)= 3.14(pie)*radius^2 C=3.14*12^2 (12 inch) = 452.16 C=3.14*8^2 (8 inch)=200.96 452.16 minus 200.96 = 251.2 in in diameter
*March 6, 2012*

**physics**

Determine the velocity of a satellite orbiting Earth at a height of 3.2 x 10^3 meters.
*March 1, 2012*

**physics**

Jessica, who mass is 55 kg, is 3.50 meters away from a 0.20 kg bag of Fig Newtons. What is the gravitational force between Jessica and the cookies?
*March 1, 2012*

**physics**

Imagine a planet that orbited the sun at a distance three times that of Earth. What would the period of that planet be in Earth years?
*March 1, 2012*

**physics**

A car is rounding a curve with a radius of 12.0 m at 8.2 m/s when it hits a slippery patch. What is the minimum coefficient of static friction between the car and the slick patch of road that will allow the car to round the corner safely?
*March 1, 2012*

**physics**

Someone swints a 3.0 kg mass at the end of a 2.3 m string in a horizontal circle. If the string can withstand a tension of 80 N, at what speed can they swing the mass before they risk a lawsuit?
*March 1, 2012*

**Thermodynamics**

Consider a system consisting of two glass bulbs, each with volume V, and each containing n moles of gas. Bulb A contains nA moles of A and bulb B contains nB moles of B (a different gas), nA = nB. The bulbs are connected by a closed stopcock. The stopcock is opened so that the...
*February 22, 2012*

**physics**

In a water balloon toss a contestant throws her balloon with a speed of 4.84 m/s at an angle of 16.5 degrees above the horizontal. Find the maximum height, the time of flight and the range of the balloon assuming her partner catches the balloon at the same height at which it ...
*February 6, 2012*

**physics **

A man is using a bow and arrow for the first time of his life. He is 25 meters from the target and aims directly at the center of the target. Surprisingly the arrow leaves the bow with a velocity of 54 m/s directly towards the center of the target and initially the velocity is...
*February 6, 2012*

**physics**

Many professional golfers can hit a golf ball 300 meters with a driver. The face of a driver and the swing pattern causes the ball to leave the club at around 18 degrees from the horizontal. Assuming the ball travels exactly 300 meters in the air before it bounces the first ...
*February 6, 2012*

**physics**

a mass being held by a string moves with speed v on a circular path of radius r, and has a period of revolution T. if it was desired to travel one revolution in twice as much time as before, what would be the radius of the path? what if the time was halved?
*January 22, 2012*

**AP Statistics **

Nurse practitioners are nurses with advanced qualifications who often act much like primary care physicians. Medical researchers wnat to design a study to compare the effectiveness of nurse practitioners and physicians. They recruit 1200 volunteer subjects for the tudy, each ...
*December 16, 2011*

**ALGEBRA**

Suppose you have a $1,000 charge on a credit card charging 1% monthly interest using the adjusted balance method. The minimum payment due in May is $70. How much will you save in interest charges in June by paying $140 instead?.
*November 26, 2011*

**microeconomics**

if the price elasticity of demand for a cup of tea is equal to 3, how would you interpret this result?
*November 17, 2011*

**Calculus**

You are the owner of a delivery company with one truck. The trucks fuel economy is 1200/x miles per gallon when driving at x miles per hour (where 80 >= x <= 110). The price of fuel is $1 per gallon. You pay the truck driver $8 per hour. If a delivery 100 miles away is ...
*November 17, 2011*

**Calculus**

OH NEVER MIND! I GOT IT HAHAHA!
*November 6, 2011*

**Calculus**

Oh i shoud've been more specific, what i meant to ask was how do you find xa, ya etc. at 1/2 hours? Thanks in advance! :)
*November 6, 2011*

**Calculus**

THANKS FOR ALL THE HELP! One question, how do you find xa,ya, xb, and yb?
*November 6, 2011*

**Calculus**

At 1:00 p.m. ship A is 25 km due north of ship B. If ship A is sailing west at a rate of 16km/h and ship B is sailing south at 20km/h, find the rate at which the distance between the two ships is changing at 1:30 p.m.
*November 6, 2011*

**chemistry**

.115 mol of solute is put in a container and water is added to give 250ml of solutrion. what is the molarity
*November 4, 2011*

**Calculus**

For question a), how did you get 12800? Where'd that come from?
*November 1, 2011*

**statistics**

What is the standard deviation of a normal distribution, whose mean is 35, in which an x-value of 23 has a z-score of -1.63?
*October 13, 2011*

**College Physics**

In this problem you will estimate the heat lost by a typical house, assuming that the temperature inside is T(in) = 20 degrees celcius and the temperature outside is T(out) = 0 degrees celcius. The walls have fiberglass insulation, which dominates the heat conduction ...
*October 8, 2011*

**College Physics**

The top layer of your goose down sleeping bag has a thickness of 5.0 cm and a surface area of 1.0 m^2. When the outside temperature is -18 degrees celcius you lose 24 Cal/hr by heat conduction through the bag (which remains at a cozy 34 degrees celcius inside). Assume that you...
*October 7, 2011*

**College Physics**

the answer is 0.027
*October 7, 2011*

**College Physics**

is k 0.023076923 ?
*October 7, 2011*

**College Physics**

The top layer of your goose down sleeping bag has a thickness of 5.0 cm and a surface area of 1.0 m^2. When the outside temperature is -18 degrees celcius you lose 24 Cal/hr by heat conduction through the bag (which remains at a cozy 34 degrees celcius inside). Assume that you...
*October 7, 2011*

**College Physics**

Nvm. I found the answer :) It's 555 W. (.200 W/m x K)(22m^2)[(19.3-16.4)/0.0230 m]
*October 7, 2011*

**College Physics**

A 2.30-cm-thick wood floor covers a 4.0 m x 5.5 m room. The subfloor on which the flooring sits is at a temperature of 16.4 degrees celcius, while the air in the room is at 19.3 degrees celcius. What is the rate of heat conduction through the floor? Use 0.200 W / m x K for the...
*October 7, 2011*

**Organic chemistry**

You are at isoelectric point for a solution of Leucine. If the number of negatively charged carboxyl ate groups, -COO-, is 1x10^19, how many positively charged amino groups, NH3+, would there be?
*October 5, 2011*

**college physics**

1 and 2 only :)
*October 4, 2011*

**Chemistry **

Why is the solubility of KHTar greater in a 0.10M NaNO3 solution than in distilled water?
*July 14, 2011*

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