# Posts by liz

Total # Posts: 1,315

**Physics waves- check answer please**

I would like to know if my answer is correct. Thanks in advanced! A person with their head sideways in the water sees a beaver slap its tail on the lake surface 1.2 km away. What is the time difference between the sound heard in the ear listening in the air and the ear hearing...

**Physics waves- check answer please**

I would like to know if my answer is correct. Thanks in advanced! A person with their head sideways in the water sees a beaver slap its tail on the lake surface 1.2 km away. What is the time difference between the sound heard in the ear listening in the air and the ear hearing...

**Physics waves- help please**

1. A person is listening to a new instrument capable of sounds ranging from 10 dB to 150 dB and with frequencies from 12 Hz to 30,000 Hz. Comment on the suitability of this instrument for the musician or audience. 2. A guitar emits a 440 Hz tone. How far apart are the crests ...

**Physics waves- check answers please**

thanks again!

**Physics waves- check answers please**

I am not too sure if my answers are correct. Here are the questions: 1. A student standing near a brick wall claps her hands and hears the echo 0.250 s later. If the speed of sound was 340.0 m/s, how far from the wall was she? For this question I got 85 m. 2. How much faster ...

**Physics waves- check answers please**

thanks a lot!

**Physics waves- check answers please**

1. In a standing wave, the medium at the tip of a loop is a) showing destructive interference b) not moving c) at the original amplitude of the wave d) showing constructive interference my answer: b 2. If a motorcycle is travelling toward an observer the frequency the observer...

**Physics waves- check answers please**

1. In a standing wave, the medium at the tip of a loop is a) showing destructive interference b) not moving c) at the original amplitude of the wave d) showing constructive interference my answer: b 2. If a motorcycle is travelling toward an observer the frequency the observer...

**Physics waves**

I am stuck with both of these questions. Thanks in advanced! 1. If one tone has a frequency of 110 Hz and another tone is played near it with a tone of 113 Hz, the beat frequency is ___ Hz 2. A standing wave has 3 nodes in a string 20 m long. The wavelength of this wave is __ ...

**Physics waves- check answers please**

thanks a lot!

**Physics waves- check answers please**

1. If a bat emits 10 sounds in 5 seconds, what is the frequency of the bat's vocal outbursts (rounded to first decimal place) My answer: 2.0 Hz 2.If one crest has a 3 cm amplitude and interacts with another pulse to produce a crest 8 cm high this demonstration" a) ...

**free-body diagram help**

A 20.0 kg block is being pushed forward on a flat surface with a force of magnitude 45.0 N against a frictional force of 13.0 N To draw this free-body diagram, would I only have the forces mentioned in the question? or would i include the -9.8m/s^2 force of gravity? Also, how ...

**Energy question**

Your friend comes across a good deal to purchase a gold ring. She asks you for advice for you to test the ring. The ring has a mass of 4.54 g. When you heat the ring with 94.8 J of energy, its temperature rises from 23.0 degrees celsius to 47.5 degrees celsius. Would you ...

**Energy question**

how could you determine the efficiency with which the mechanical energy of a pendulum is conserved?

**word problem**

If equal amounts of heat are added to equal masses of silver and copper, both at the same initial temperature, which will reach the higher final temperature? Explain your answer. The specific heat capacity of silver is 0.235 J/g degree Celsius and that of copper is 0.385 J/g ...

**Energy question**

thanks a lot! you gave me some good ideas! and i agree with you about the fluorescent light bulbs. They don't last as long as the box says

**Energy question**

How would a $10.00 compact fluorescent light bulb (15 W) be an overall money saver compared to an incandescent light bulb (60 W) that costs $0.50?

**Energy multiple choice question**

Which of the following samples has the highest specific heat capacity? a) A 100 kg sample of lead requires 13 000 J to increase its temperature by 1 K b) A 50 g sample of water releases 1050 J as it cools by 5 degree Celsius c) A 2 kg sample of copper receives 2340 J of ...

**Physics Energy**

How would a $10.00 compact fluorescent light bulb (15 W) be an overall money saver compared to an incandescent light bulb (60 W) that costs $0.50?

**physics**

Show that the acceleration is 7.5 m/s2 for a ball that starts from rest and rolls down a ramp and gains a speed of 30 m/s in 4 s

**chemistry**

Sodium metal adopts a body-centered cubic structure with a density of 0.97g/cm3. A. Use this information and Avogadro's number to estimate the atomic radius of sodium. B. If it didn't react so vigorously, sodium could float on water. Use the answer from part a to ...

**english**

May you please edit this essay? Holden Caulfield in “Catcher in the Rye”, seems to be obsessed with mortality and youthful innocence, both of which are embodied in James Castle and Allie Caulfield. Holden demonstrates these infatuations in his conversation with ...

**HELPPPP NOOWW !!!!!**

Are you doing K12 8th grade grammar?

**computers**

is it 1.A 2.C 3.A

**chemistry**

how to calculate the amount of heat in calories absorbed when 50.0 g of water at 20 degrees C spreads over your skin and warms the body temperature, 37 degrees C

**Physics**

A ball is fastened to one end of a 30cm string, and the other end is held fixed to a support. the ball whirls in a horizontal circle. Find the speed of the ball in its circular path if the string makes an angle of 30 degrees to the vertical.

**chemistry**

A room contains 48 kg of air. How many KWh of energy are necessary to heat the air in the house from 7oC to 28oC? The heat capacity of air is 1.03 J/goC

**Differential Equations**

Solve dy/dx = y/(2y-x) using rational substitution (using v=y/x) with the initial condition y(0)=1. I solved this problem and found C (the constant) to be undefined. That is not the correct answer.

**Physics**

Ohhh I see what I did wrong! Thanks a lot again!

**Physics**

I was wondering if my answers are correct. 1. A 50kg person is taking a ride on an elevator travelling up at a steady speed of 2.5m/s. Find the time fo the elevator trip if the elevator does 4900 J of work on the person. My answer: First I used the formula f=mg to find the ...

**Physics**

thanks a lot!

**Physics**

I was wondering if my answers are correct. Thanks in advance. 1. A boy pushes down on a car rolling horizontally down the road. The boy pushes down vertically with 10N of force as the car rolls 3.0m horizontally. What work is done? my answer: 30 N•m (or would it be -30N&#...

**Linear Algebra!**

Write in parametric form the equation of the line that is perpendicular to r=(2i + 4j) + (i - 2j)t and goes through (1,0)

**Calculus**

write and row reduce the augmented matrix to find the general solution: 2x - z = 2 6x + 5y + 3z = 7 2x - y = 4

**Calculus**

write and row reduce the augmented matrix to find the general solution: x - 2y + 13 = 0 y - 4x = 17

**math-advanced functions**

on my exam review, i have this question for composition of functions Given f(x)=3x^2+x-1, g(x)=2cos(x), determine the values of x when f(g(x))=1 for 0≤x≤2π.

**Algebra**

Determine the equation of g(x) that results from translating the function g(x)f(x)=x^2 +3 upward 10 units 1) g(x)=(x+13)^2 2) g(x)= (x+15)^2 3) g(x)= (x+4)^2 -11 4) g(x)= (x+4)^2 +11

**Math. I really don't get this question**

three circles are manually tangent externally. their centers form a triangle whose sides are of length 8, 9, 13. find the total area of the three circles

**Fundamental Theorm of Calculus**

Find the average value of f(x)=3x^2-2 x on the interval [3,6]

**Fundamental Theorm of Calculus**

Use a definite integral to find area of the region under the curve y=7-4x^2 and above the x-axis. Thanks in advance!

**Physics**

A test tube in a centrifuge is pivoted so that it swings out horizontally as the machine builds up speed. If the bottom of the tube is 165.0 mm from the central spin axis, and if the machine hits 53500 rev/min, what would be the centripetal force exerted on a giant amoeba of ...

**physics**

A bicyclist traveling at 8 m/s rides around an unbanked curve. The coefficient of friction (is this static or kinetic friction?) between the tires and the road is 0.42. What is the radius of the shortest turn that the bicyclist can safely make?

**Math**

3x^2

**Math**

what is the solution of 3x^+27=0

**pre-calc**

prove or disprove cos(x-y)=cos(x)-cos(y)

**Math**

You place a mirror on the ground 6 feet from the lamppost. you move back 3 feet and see the top of the lamppost in the mirror. What is the height of the lamppost?

**American Government**

Legislation whose tangible benefits are targeted solely at a particular legislator's

**Calculus-Aproximate Areas**

Estimate the area under the graph of f(x)=sin(pix) from x=0 to x=1 using the areas of 3 rectangles of equal width, with heights of the rectangles determined by the height of the curve a a) left endpoint: b) right endpoint:

**Calculus-Aproximate Areas**

I tried that, and it was incorrect

**Calculus-Aproximate Areas**

Estimate the area under the graph of f(x)=sin(pix) from x=0 to x=1 using the areas of 3 rectangles of equal width, with heights of the rectangles determined by the height of the curve at a) left endpoint: b) right endpoint:

**Calculus-Approximate areas**

Estimate the area under the graph of f(x)= x^2 + 3 x from x=1 to x=10 using the areas of 3 rectangles of equal width, with heights of the rectangles determined by the height of the curve at a) left endpoints: b) right endpoints:

**Calculus-Newton Method Approximation**

Use Newton's method to approximate the positive value of x which satisfies x=2.3cosx Let x0=1 be the initial approximation. Find the next two approximations, x_1 and x2, to four decimal places each.

**Calculus-Applied Optimization Problem**

The manager of a large apartment complex knows from experience that 100 units will be occupied if the rent is 425 dollars per month. A market survey suggests that, on average, one additional unit will remain vacant for each 9 dollar increase in rent. Similarly, one additional ...

**Math**

How do I work out:if life expectancy of male is 78.9 and female is 83.6. Life expectancy is % lower than female. What is formula please

**statictics**

The ABC Self-Concept Inventory has a split-half reliability coefficient of 0.90, and the XYZ Self-Concept Inventory has a Spearman-Brown reliability coefficient of 0.90. If all other factors are equal, which instrument would you choose to use?

**Physics**

A research balloon of total mass 225 kg is descending vertically with a downward acceleration of 1.4 m/s2. How much ballast must be thrown from the car to give the balloon an upward acceleration equal to 3.6 m/s2, presuming that the upward lift of the balloon does not change.

**calculus**

relative maxima and relative minima 2x^2+ 4000/x +10

**cinquain poem**

thanks for your help and advice

**cinquain poem**

For social studies we had to make our own 4 topic of cinquain poems. I asked some people and not many knew this type of poem, but one person said it all seem good except for the last lines. Do you think I did the format corret? Thanks for your help 1.Homesteaders Brave, ...

**Math**

-10 + 6g = 110

**math**

I have fewer ones than tens. the value of my tens is 20 what two numbers can I be

**Physics**

In a vacuum, two particles have charges of q1 and q2, where q1 = +3.8C. They are separated by a distance of 0.37 m, and particle 1 experiences an attractive force of 4.7 N. What is the value of q2, with its sign? Two spherical objects are separated by a distance of 1.45 ×...

**cerritos**

political culture refers to

**Calculus 2**

A tank is full of water. Find the work W required to pump the water out of the spout. (Use 9.8 for g and 3.14 for π. If you enter your answer in scientific notation, round the decimal value to two decimal places. Use equivalent rounding if you do not enter your answer in ...

**Calculus 2**

Use the method of cylindrical shells to find the volume V generated by rotating the region bounded by the given curves about x = 4. y = 3 x^4 y = 0 x = 2

**Franklin High**

4x - y = 2, 9x - 2y = 8 find solution by substitution method

**Calculus help!**

Does the limit of xy/(x^2 + y^2) exist as (x,y)--->(0,0)? Why or why not??

**Calculus help!**

Three forces with magnitudes 75 pound, 100 lb, and 125 pound act on an object at angles of 30 degrees, -45 degrees, and 120 degrees respectively. Find the direction and magnitude of the resultant vector.

**Calculus**

Describe the surface and give traces: x = y^2 - 4z^2

**Calculus-PLZ help!**

Given u=3i-2j+k,v=2i-4j-3k, w=-i+2j+2k, 1 Find a unit vector normal to the plane containing v and w. 2 Find the volume of the parallelepiped formed by u, v, and w. 3 Are any of these vectors parallel? Orthogonal? Why or why not?

**Find the center (h,k) and radius**

Find the center (h,k) and radius r of the circle and then use these to (a) graph the circle and (b) find the intercepts, if any. 3x^2+36x+3y^2=0

**Calculus**

Describe the following surface and give traces if available. x^(2)-4z^(2)=4

**math**

Here are the answers Combinations Quiz For conexus: 1.C 2.A 3.C 4.D 5.D 6.B 7.D 8.B 9.C If you want show get some wrong on purpose so you teacher won't get suspicious. :)

**Statistics**

You have a ten question multiple choice test in your next class and you did not study at all. Each question has four choices and only one correct answer. You are going to guess on each question. What is the probability that you score at least a 20% on the test.

**math**

245 = .25x not sure how to do this since I have only learned with ratios

**Chemistry II**

Arrange the following 0.10M solutions in order of increasing pH: a. Nacl b. NH4CL C. HCL D. NaCH3CO2 e. KOH

**College chemistry**

The pH of blood is 7.4 and that of saliva is 6.4. what is the difference in pH between these two solutions? How much more Hydronium ion (H3O+) is in the saliva than in the blood. I need a detailed answer with the formulas if you can. I have a hard time with chemestry

**Chemistry**

Thank you :) this helped a lot!

**Chemistry**

Can you explain it better we JUST started this section and im having a hard time with knowing what to put where when it comes to the solutions. what is the acid and what is the base

**Chemistry**

The pK3 of formic acid is 3.75 A)what is the pH of a buffer in which formic acid and sodium formate have equimolar concentration? B)what is the pH of a solution in which the sodium formate is 10M and the formic acid is 1M?

**statistics**

What is the probability that 10 of 100 apples will be < 130 g? mean=173 std deviation=34?

**Science**

For an Indian Youth Environment camp essay why should someone be chosen to go?

**chemistry**

calculate the yield of CO2 if 30.g of C2H6 reacts with 14.0g of O2. Show work

**Calculus**

Find the arc length of the curve described by the parametric equation over the given interval: x=t^(2) + 1 y=2t - 3 0<t<1

**Calculus help!**

On what intervals of t is the curve described by the given parametric equation concave up? Concave down? x=t^2; y=t^(3) + 3t I am a bit confused on how to solve this...any help/explanations are welcome!! (& greatly appreciated!)

**Calculus**

Find the arc length of the curve described by the parametric equation over the given interval: x=t^(2) + 1 y=2t - 3 --> 0<t<1

**Calculus**

Convert the polar equation to rectangular coordinates: r = 2-cos theta ...and find all points of vertical and horizontal tangency.

**Calculus**

Find the arc length of the curve described by the parametric equation over the given interval: x=t^(2) + 1 y=2t - 3 ...0 < t < 1

**Calculus**

On what intervals of t is the curve described by the given parametric equation concave up? Concave down? x=t^2; y=t^(3) + 3t I am a bit confused on how to solve this...any help/explanations are welcome!! (& greatly appreciated!)

**Calculus**

Convert the curve to an equation in rectangular coordinates: x=(t+2); y=-2sqrt(t)

**Parametric Equations**

Find the length of the curve over the given interval: x=t+1 y=ln cos(t) for t=0 ---> t=pi/4

**calculus**

Find the length of the curve over the given interval: x=t+1 y=ln cos(t) for t=0 ---> t=pi/4

**Calculus**

Convert to a rectangular equation by eliminating the parameter: x=sin(theta) y=(cos theta)^2

**Statistics**

The Boeing 757-200 ER airliner carries 200 passengers and has doors with a height of 72 inches. Heights of men are normally distributed with a mean of 69 inches and a standard deviation of 2.8 inches. b) assume that half of the 200 passengers are men, what doorway height ...

**Math- Ms Sue can you help**

so the volleyball team had a standard deviation 2.39 and a mean of 68.2 ( I messed up when giving you the numbers, there should have been a comma between 69 &70 not a period-giving 10 numbers) The dance team I got 3.05 standard deviation and a mean of 63 So the should the ...

**Math-**

I didn't do the standard deviation for each one because I didn't know how, can you help?, if not do you have something ( a link to forward me to) so I can review standard deviations. I do appreciate your help.

**Math- Ms Sue can you help**

Here is the height, in inches, of 10 randomly selected members of the girls' dance team and 10 randomly selected of the girls' volleyball team Based on the interquartile ranges of the two sets of data, which is a reasonable conclusion concerning heights of the players ...

**math- Reiny can you help**

can you help with the above question

**math- please help**

Here is the height, in inches, of 10 randomly selected members of the girls' dance team and 10 randomly selected of the girls' volleyball team Based on the interquartile ranges of the two sets of data, which is a reasonable conclusion concerning heights of the players...

**math**

Here is the height, in inches, of 10 randomly selected members of the girls' dance team and 10 randomly selected of the girls' volleyball team Based on the interquartile ranges of the two sets of data, which is a reasonable conclusion concerning heights of the players ...