# Posts by help

Total # Posts: 1,481

Math
A truck tire travels about 11 feets in 1 full rotation. What is the diameter of the wheel, to the nearest inch?

physics
A 1300 sports car accelerates from rest to 95KM/H in 7.0S .What is the average power delivered by the engine?

chemistry
what is the total number of joules released when a 5.00 gram sample of water changes from liquid to gas at 100 degrees Celsius?

physics
Assume that the pressure is one atmosphere and determine the heat in joules required to produce 3.23 kg of water vapor at 100.0 °C, starting with (a)3.23 kg of water at 100.0 °C and (b)3.23 kg of liquid water at 0.0 °C

physics
A piece of glass has a temperature of 72.0 °C. Liquid that has a temperature of 37.0 °C is poured over the glass, completely covering it, and the temperature at equilibrium is 50.0 °C. The mass of the glass and the liquid is the same. Ignoring the container that ...

Physics
A cube of solid aluminum has a volume of 1.00 m^3 at 20 degree C. What temperature change is required to produce a 100-cm^3 increase in the volume of the cube? I know you are supposed to use: DeltaV=Beta*Vo*DeltaT. But I don't know what Beta is and the ones I have found ...

PHYSICS
A toy car in the figure below runs off the edge of a table that is h = 1.375 m high. The car lands d = 0.375 m from the base of the table.How fast was the car going on the table?

PHYSICS
You accidentally throw your car keys horizontally at 10.0 m/s from a cliff 78 m high. How far from the base of the cliff should you look for the keys?

physics
an arrow of mass .04 kg is pulled back 10 cm in the bow, having a force of 25.2 N. It is released 1.5m from the ground...how far will the arrow fly? (all of the energy from pulling it back converts into the flying arrow)

Physics
Rubber Band A 156 g hockey puck is attached to a rubber band and rotated with an angular speed of 9.8 rad/s on frictionless horizontal ice. It takes a force of 1.12 N to stretch the rubber band by 1 cm. (a) If the original length L of the rubber band is 1 m, by how much (in m...

chemistry
thanks for the explanation!!!

chemistry
2. A 350 mL buffer solution containing 0.15 M HF and 0.150 M NaF is reacted with sodium hydroxide. What mass of NaOH can this buffer neutralize before the pH rises above 4.0? If the same volume of buffer was 0.35 M in HF and 0.35 M in NaF then what mass of NaOH could be ...

chemistry
For each of the following solutions, calculate the initial pH and the final pH after adding 0.010 mol of HCℓ. a) 500.0 mL of pure water i'm not sure how to do this question.. would the equation be h20+h30 equilibrium arrows h30+h20

physics
A 910 kg sports car slows down to 6.0 m/s to read a cross street sign. The 1440 kg pick-up truck following the sports car fails to see that the sports car has slowed and continues traveling at 17.0 m/s. The pick-up slams into the sports car. With what velocity will the two ...

physics
i read the question wrong..thank for the help

physics
A 45.00 kg child standing on a frozen pond throws a 0.60 kg stone to the east with a speed of 5.80 m/s. Neglecting friction between child and ice, what is the speed (in m/s) of the child after throwing the stone? I'm kind of confused about the masses..

CAL 1
DERIVATIVE f(x)=4t+1 (x,x+2)

cal 1
Find the area of the indicated region f(x)=(4-x^2) between(0,2)with 4 equal subintervals (left endpoints)

math
find all points on the hyperbola y=1/x, that are closest to the origin on (1/2,2)

cal 1
f(x)= (1-sinx) interval (0≤x≤2π) find where the function is increasing decreasing.. i know that f`(x)=1-sinx it is equal to zero when x=pi/2 im stuck there..

chemistry
oops..i posted this question twice

chemistry
a 5.55g sample of a weak acid with ka=1.3*10^-4 was combined with 5.00ml of 6.00 M NAOH and the resulting solution was diluted to 750mL. The measured pH of the solution was 4.25. what is the molor mass of the weak acid. if used the formula pH=kpa+log(base/acid) Ph=3.89+log(6....

chemistry
a 5.55g sample of a weak acid with ka=1.3*10^-4 was combined with 5.00ml of 6.00 M NAOH and the resulting solution was diluted to 750mL. The measured pH of the solution was 4.25. what is the molor mass of the weak acid. if used the formula pH=kpa+log(base/acid) Ph=3.89+log(6....

chemistry
A 20ml sample of .125M diprotic acid solution was titrated with .1019M KOH.the constants for the acid are k1=5.2*10 ^-5 and K2=3.4*10 ^-10. What added volume of base does each equivalence point occur? i got .0254L for the first one and .0508 for the second. Can anyone check if...

physics
What is the original compression distance of the spring? Thought it would be zero but that isn't right.

physics
a 3.5 kg block is accelerated from rest by a compressed spring of spring constant 640 N/m. The block leaves the spring at the springs relaxation length.The block then travels over a horizontal floor with coefficient of kinetic friction 0.25. The friction force stops the block...

physics
never mind i got the question:)

physics
A 2.606 kg block is on a horizontal surface with ìk = 0.160, and is in contact with a lightweight spring with a spring constant of 577 N/m which is compressed. Upon release, the spring does 7.212E-1 J of work while returning to its equilibrium position. I found the ...

physics
the next part is What is the speed of the block when it hits the spring? i did 1.42=.5mv^2(final)-.5mv^2(initail) The final velocity woulf be zero so 1.42=.5(2.8)v^2 v=1.01 im not sure what i did wrong

physics
A moving 2.8 kg block collides with a horizontal spring whose spring constant is 215 N/m (see figure). The block compresses the spring a maximum distance of 11.5 cm from its rest position. The coefficient of kinetic friction between the block and the horizontal surface is 0.48...

physics
The force F = (3.2, -7.1) N acts on a mass of 1.15 kg. At time t = 0 s, the mass has a velocity v0 = (-0.46, 0.36) m/s. What is the initial kinetic energy (in J)? i know that k=.5mv^2 so the answer i got was (.12167,0.07452) but i'm not sure what to do from there?

physics
The force F = (3.2, -7.1) N acts on a mass of 1.15 kg. At time t = 0 s, the mass has a velocity v0 = (-0.46, 0.36) m/s. What is the angle (in degrees) of the initial velocity, measured counter-clockwise from the +x-axis? I got 38.04 degrees but isn't the right answer

physics
A 2.20 kg box slides down a rough incline plane from a height h of 1.39 m. The box had a speed of 2.77 m/s at the top and a speed of 2.34 m/s at the bottom. Calculate the mechanical energy lost due to friction

physics
A constant force of 48.7 N, directed at 34.1° from horizontal, pulls a mass of 15.1 kg horizontally a distance of 2.77 m. Calculate the work done by the force.

math
A painter leans a ladder against a vertical wall. The top of the ladder is 7 meters above the ground. When the bottom of the ladder is moved 1 meter farther away from the wall, the top of the ladder is 5 meters above the ground. What is the length of the ladder? Round to the ...

math
Three rectangles have exactly the same area. The dimensions of each rectangle (as length and width) are a and b; a – 3 and b + 2; and a + 3 and b – 1. Find the area of the rectangles.

math
Three rectangles have exactly the same area. The dimensions of each rectangle (as length and width) are a and b; a – 3 and b + 2; and a + 3 and b – 1. Find the area of the rectangles.

Physics
A cylinder with a piston is filled with ideal gas. The gas temperature is held at 450 K. The cylinder is heated by an oven through a square metal rod connected between the oven and the cylinder. The rod has sides d = 2 cm and length L = 2.3 m. (a) If the oven is held at 850 K...

chemistry
For all deexcitations that result in the visible spectrum of hydrogen, what is n ?

chemistry
The X-X bond energy in the hypothetical gas, X2 is 153 kJ/mol. a. How much energy, in joules, is required to break the bond in a single X-X molecule? b. What wavelength of electromagnetic radiation would have the energy required to break the X-X bond? c. In what region of the ...

chemistry
The red line in the Helium spectrum is longer than the red line in the hydrogen spectrum. What does that tell us about the distance between n2 and n3 in helium as compared with the distance between n2 and n3 in hydrogen?

chemistry
In the emission spectrum of hydrogen, some lines are in the infra red range. h l Suggest an electron transition (specify n and n) that is in this range and calculate its corresponding wavelength and delta E.

algebra
are you sure? thank you :)

bobpursley???
i did that and i also wrote the answers next to each question and i just want to know if they are right. are they right? please respond

science
what is the difference between a control and a variable

science
thank you :)

science
what is concentration please say it in an easy to understand answer thank you!

According to the U.S. Census Bureau in 2009 there were 21,854,374 veterans in the United States. Veterans of the Korean War accounted for 12.4% of that total, while 10.7% were veterans of World War II. What is the positive difference between the numbers of veterans of the ...

math
According to the U.S. Census Bureau in 2009 there were 21,854,374 veterans in the United States. Veterans of the Korean War accounted for 12.4% of that total, while 10.7% were veterans of World War II. What is the positive difference between the numbers of veterans of the ...

the horizontal range of a projectile is 4 root 3 times of its maximum height. calculate the angle of projection.

if action and reaction are always equal and opposite, why don't they always cancel each other and leave no force for acceleration of the body?

find the value of 60 joule per minute on a system which has 10 cm,100gm, and 1 minute as fundamental units.

thank you so much drbob222. u are a genius. could you check out my physics questions too?

a vessel contains 12 gm of methane gas at t degree celcius temp. and 1 atm. pressure. when the temp. is increased by 10 degree celcius at the same volume, the pressure increases by 10%. calculate the volume and initial temp.

math
when is these rational function equal to zero? 6x^2/(x^3+1)^2=0 -2x/(x^2-1)^2=0

math
verify that the function satisfies the hypothesis of the mean value theorem on the given interval. then find all numbers c that satisfy the conclusion of the mean value theorem. f(x) = x/(x+2) , [1,4]

calculus
use the methods of this section to sketch the curve. y=x^3-3a^2x+2a^3, where a is a positive constant. What do the members of this family of curves have in common? How do they differ from each other?

Statistics
Are these statements true or false? 1. The sample mean, the sample proportion and the sample standard deviation are all unbiased estimators of the corresponding population parameters. 2. If the population is normally distributed with known variance then the sample mean may not...

math
what is the best parking space/shortest that would take the from store 1 to store 2 and back to the car?use the following information: -the distance between store 1 to store 2 is 25 yds wide. -driveway between the sidewalk and parking lot is 10 yds this all they give me please...

Math
y = |x − 4| + 8 Find the x-coordinate of the vertex of the graph. And the y-coordinate of the vertex of the graph. Please help me, I'm stuck!

HIstory
Why did congress feel that construction was a confessional task and not a presidential task?

spanish
what am i doing wrong??

spanish
¿Quién va a preparar la ensalada? Mirta y Lidia Your response: mirta y lidia las va a preparar 3.¿Quién va a cocinar la paella? Alberto y su novia Your response: alberto y su novia los va a cocinar. ¿Quién va a limpiar el apartamento ...

Halloween
It's saturday and halloweens tomorrow. But I was wondering is trick or treating sopost be today or tomorrow? I've heard peolple going today and many people say tomorrow. I know sunday is an school night and some people wiill be at church. I have no idea if I should ...

CALC HARD...
Suppose that 430 ft of fencing is used to enclose a corral in the shape of a rectangle with a semicircle whose diameter is a side of the rectangle. (In the figure below, the blue outline represents the fencing.) Find the dimensions of the corral with maximum area. x= y=

CALC HARD...
Suppose that 430 ft of fencing is used to enclose a corral in the shape of a rectangle with a semicircle whose diameter is a side of the rectangle. (In the figure below, the blue outline represents the fencing.) Find the dimensions of the corral with maximum area. x=? y=? i ...

CALC HARD...
i did get that and i got farther than that but then got completely lost

CALC HARD...
Suppose that 430 ft of fencing is used to enclose a corral in the shape of a rectangle with a semicircle whose diameter is a side of the rectangle. (In the figure below, the blue outline represents the fencing.) Find the dimensions of the corral with maximum area. x=? y=? i ...

chemistry
consider the following reactions O+N2->NO+N Ea=315kj/mol Cl+H2->HCl+H Ea=23kj/mol Why is the activation energy for one much lower that the other. The frequency factor is very close in value for the two. Assume they are the same compute the ratio of the reaction constants...

cant post a question
i tried posting a question but it says that i cant have links in my question but i didn't have any? Anyone know hat to do?

chem/math
thanks that helps alot

chem/math
I need to fid the activation energy but i forgot how to solve for Ea 4.58*10^-15=e^(Ea/2537.02) can you show the work thank you

Management
what economic, social , and political forces have made employee traininng even mor eimportant today than in the past?

calculus
find the absolute maximum and minimum values of f on the given interval f(x)= (x^2-4)/(x^2+4), [-4, 4]

physics
Mary and John are on opposite sides of a seesaw. Mary has 3x the mass of John. If Mary is sitting at a distance of .5m from the fulcrum, how far must John site in order to keep it balanced.

calculus
Use a linear approximation (or differentials) to estimate the given number (2.001)^5

physics
A 70kg man stands on a bathroom scale in an elevator. As the elevator starts moving, the scale reads 90kg Is the elevator acceleration up or down, is the elevator moving up or down?

phsics can someone check if i did it right
A block of wood of mass 3kg is on a rough incline of 37degrees. Find the min value of the coefficient of static friction for the block to remain stationary? Fn=3*9.8cos37 Fn=23.4 3*9.8sin37-us(23.5)=0 us=.743

phsics
A block is at rest on an inclined plane whose elevation can be varied. The coefficient of static friction is μs= 0.4, and the coefficient of kinetic friction is μk = 0.16. The angle of elevation θ is increased slowly from the horizontal. At what value of θ ...

Stats-BOB PURSLEY Help, do you know this?
Is there a rule to figure out if this is a true or false statement? A sample size of 900 is not large enough to conclude that the sampling distribution of p is a normal distribution, when the estimate of the population proportion is .995.

Physical Science
Pitch is to make a plane descend or climb. The pilot adjusts the elevators on the tail to make a plane descend or climb. Lowering the elevators caused the airplane's nose to drop, sending the plane into a down. Raising the elevators causes the airplane to climb.

chemistry
Never mind i figured it out:)

chemistry
To what final volume should you dilute 50.5ml of a 4.75 M KI solution so that 27.5ml of the diluted solution contains 3.10g of KI

Ap Chemistry
:) Thanks you so much! :)

Okay, sorry....I posted it again correctly :)

chemistry
Its just a general question. I'm trying to get the van't hoff factor and i think you need to know number of ions present. for example how do you know the # ions present in k2s

chemistry
How do you know the number of ions present in a compound.

Chemistry
Calculate the number of molecules in 3.1466x10^1 grams of sulfur dioxide, SO2

Chemistry
Calculate the number of molecules in 3.1466x10^1 grams of sulfur dioxide, SO2

Chemistry
calculate the grams of sodium in 17.606 g of Na2CO3

88.8 or if you round 89

all but a circle

Physics
A speedboat starts from rest and accelerates at 2.689x10^0 m/s2 for 6.5062x10^0 seconds. After that, the boat then accelerates at 1.7853x10^0 m/s 2 for 3.1299x10^0 seconds. What is the velocity of the boat at the end of this, expressed in 4 significant figures?

chemistry

chemistry

chemistry

math
math box! 5=15 10=25 15=35 20=45 25=55 what is the rule

science
try chicken wire

Physics
A car travels a total distance of 3.22911x10^2 m to the East in 6.7135x10^1 s. What is the speed of the car, in m/s with 4 significant figures? Note: Your answer is assumed to be reduced to the highest power possible. Your Answer: x10

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