Tuesday

February 28, 2017
Total # Posts: 512

**Physics**

Ohm's law can be stated as: (resistance in ohms)= (voltage in volts)/(current in amps) . For part (a): resistance=(1.5V)/(25A)=0.06 ohms Use the same equation for (b) and (c).

*February 12, 2008*

**Physics**

You are on the right track. Your conversion to m/s looks good. The question is how far does the car move in 0.71s. distance = rate*time = 16.111m/s * 0.71s =11.44m

*February 11, 2008*

**Speed and distance**

You have it figured out. 47(r-5)+9r=5r(r-5) 47r-235+9r=5r^2-25r Rearranging and combining you had an error. I got 5r^2-81r+235=0 Solve using the quadratic formula. One of the solutions of the quadratic will be less than 5 which would imply that the canoe would change ...

*February 9, 2008*

**chem**

Google is your friend. google: solute solution Read all of the first hit (Wikipedia).

*February 8, 2008*

**chemistry**

google for: solute solution Read all of the first hit.

*February 8, 2008*

**Physics II**

power = (voltage^2)/resistance

*February 8, 2008*

**Physics**

The formula for resistance is: total resistance = (resistivity) * (length)/(area) filling in from the problem statement: 0.32 ohms = (resistivity) * 1m/(area) looking up the resistivity for tungsten: at 20 C restivity = 5.28 * 10^-8 ohms*m leaving just the area unknown: 0.32 ...

*February 8, 2008*

**math**

For the first problem: x=length of side before the addition x+4=the length of the longer side after the the additional 4 feet is purchased. The new area of the property is: x(x+4)=9600 x^2 + 4x =9600 x^2 + 4x - 9600=0 which is: (x-96)(x+100)=0 Ignore the negative solution for ...

*January 29, 2008*

**Physics**

Also, it is assumed there is no friction with the ramp.

*January 28, 2008*

**Physics**

The initial potential energy of the watermelon is mass*acceleration*height or mgh for Earth. For practical purposes assume that total energy of the watermelon is constant. So the potential energy + the kinetic energy is constant. The kinetic energy is given at the point of ...

*January 28, 2008*

**science**

assuming there are no other forces (ignoring friction between the skates and the ice) force=mass*acceleration so... acceleration=force/mass acceleration=234n/45kg=??

*January 24, 2008*

**C++ Programming**

Nope, for some reason the last lines which are not posting. Anyway, the last lines are the same as your source.

*January 23, 2008*

**C++ Programming**

I guess the double blank lines caused the posting applet to clip the last two lines. Here they are finally, I hope. -------------------- return 0; }

*January 23, 2008*

**C++ Programming**

missed the end ------------------------- #include <tchar.h> #include <iostream> using namespace std; int _tmain(int argc, _TCHAR* argv[]) { cout << "-Calculate the area of a circle-" << endl; cout << endl; cout << "Radius = &...

*January 23, 2008*

**C++ Programming**

I did a quick check using MS VS2005. The following compiles correctly. Changing the line: cout<<endl; to: cout<<end; gives a compile error -------------------------------- Below compiles using VS2005 -------------------------------- #include <tchar.h> #...

*January 23, 2008*

**C++ Programming**

Did you intend for the line: cout<<end; to really be: cout<<endl;

*January 23, 2008*

**math**

x=first number y=second number 3*x + y = 18 2*x - y = 12 You need to eliminate one of the variables and solve for the remaining one. In this problem, you can see that if the two equations are added together, the y variable is eliminated: adding: 3x + y = 18 2x - y = 12...

*January 23, 2008*

**calc**

To check--differentiate the integral to see if you get the original equation. I believe you are correct.

*January 22, 2008*

**math... help plz (not hard)**

Each time you multiply a number by itself you increment the exponent: A*A=A^2 Each time you divide a number by itself you decrement the exponent: So... (A^3)/A = A^2 (A^2)/A = A^1 = A A/A = 1 = A^0 Hope this helps. A

*January 22, 2008*

**algebra**

cost=(one time charge) + (charge per frisbee) * (number of frisbees) So: c = $7.00 + f * $1.50

*January 21, 2008*

**Trig**

Sorry, the diagram didn't survive the font change.

*January 10, 2008*

**Trig**

The first problem: Sketch this problem to make it easier to visualize. There is a rectangular frame with the inside dimensions of 12 * 16 inches. The frame has a width of W. You need to divide the frame into pieces and then write an equation for those pieces to equal 165 in^2...

*January 10, 2008*

**Math**

Integer coeffecients means numbers with no decimal part. Recall that an equation is still valid if you multiply both sides by the same value. For the coeffecients of X (6.2 on the left and 3.8 on the right) what would be required to change those to 62 and 38 respectively?

*January 7, 2008*

**Math**

To find the actual tablespoons per serving, divide the total tablespoons used by the total servings: (3 tablespoons)/(1.5 servings) =3/1.5 tablespoons/serving =?? tablespoons/serving

*January 7, 2008*

**math/formula 1**

Area of a triangle: Area=(base * height)/2 Area of a trapezoid: Area=height * (b1 + b2)/2 where: b1=length of top side b2=length of bottom side

*January 5, 2008*

**Physics**

Find the potential energy given to the object when the rope is pulled to the side. This is just the height difference. The new distance from the ceiling is 1.5m * sin(35). The original distance was just the rope length (1.5m). Use mgh for the potential energy gained. Now, at ...

*January 3, 2008*

**Physics**

I get a different answer for acceleration. Check your conversion from 57.0 km/hr to ?? m/s.

*November 26, 2007*

**algebra 2**

Usually, the radical sign defaults to mean the squres root. So, the question is for what values of x is the square root of (2x-10) a real number. The square root is real for all non-negative values. So, for what values of x will (2x-10) be non-negative? What is the smallest ...

*November 25, 2007*

**physics**

The net force on the pilot is just the familiar f=ma. The mass of the pilot is given. The acceleration of the pilot should be the same as the acceleration of the plane. The forumula f=ma can be rearranged to a=f/m. f and m are given for the plane. Solve for the acceleration of...

*November 17, 2007*

**math**

A way to solve this type of problem: First express one of the variables in terms of the other. -x-y = 5 or, y = -5-x Now substitute that value for y into the other equation. 2x -(-5-x)=-4 Solve for x, then substitute the known x value into either equation to solve for y.

*November 1, 2007*

**Physics**

Find the cubic meters water volume of the water bed. Do this by multiplying its width * length * height. Water weighs 1000kg/m^3, convert the volume to kg of mass. The force on the floor will be F=m*g. Is this > 6660N ?

*November 1, 2007*

**Physics**

BobPursley--Thanks for correcting it! I was in too much of a hurry.

*October 29, 2007*

**Physics**

f=ma f=force m=mass a=acceleration therefore, m=f/a The values for force and acceleration are given in the problem. Plug them in to get mass.

*October 29, 2007*

**Physics**

I just replied to the previous post. The roots I got for the quadratic were +4.875 and -3.854,

*October 27, 2007*

**Physics**

For the roots of the quadratic I got +4.875 -3.854

*October 27, 2007*

**Physics**

The displacement of the safety spring has to be considered in the total potential energy of the elevator car.

*October 27, 2007*

**Physics**

Your approach looks OK. Check for any errors in copying the problem or any math errors.

*October 27, 2007*

**physics**

U1=(1/2)(37.0)N/cm (3.10cm)^2 U2=(1/2)(18.5)N/cm (s cm)^2 U1=U2 2 * (3.10cm)^2 = (s cm)^2 19.22 cm^2 = s^2* cm^2 s = +- sqrt(19.22) s = +- 4.38cm

*October 27, 2007*

**Science**

Your answer is correct. Be sure to use the units of amps as the current.

*October 27, 2007*

**Physics**

That is correct.

*October 27, 2007*

**Physics**

Voltage is measured in volts, current is measured in amps, and resistance is measured in ohms. Ohms law says the relationship between these three items is: V = I * R where V = voltage in volts I = current in amps R = resistance in ohms The equation can be rearranged to find ...

*October 27, 2007*

**Physics**

The unit of currents is amps.

*October 27, 2007*

**Physics**

amps = volts / ohms = 1.5/1000 amps =0.0015 amps

*October 27, 2007*

**Physics**

Use ohm's law: voltage = current * resistance arranging for current: current = voltage / resistance

*October 27, 2007*

**Physics**

3. 12 watts is not correct A 4 ohm resistor carrying 3 amps has a voltage drop of 3 * 4 or 12 volts. The current throught the resistor is 3 amps. Volts * Amps = 3 * 12 = 36 Watts. 4. AC voltage is easily changed with a transformer. High voltage is good for long distance ...

*October 24, 2007*

**Physics**

1. 30 volts is correct 2. 6.87 is not correct For parallel resistors, 1/RT = 1/R1 + 1/R2 + 1/R3... For two resistors, 4 ohm and 6 ohm 1/RT = 1/4 + 1/6

*October 24, 2007*

**math**

First, how far did Marla walk? The library is 4 miles. So, the halfway point woud be? Let D be the halfway distance. Time=distance/speed Time = D/(3 mi/h)

*October 23, 2007*

**math**

Your answer looks OK, but you might want to redo your equation: 50h + 60h = 330. It has no meaning.

*October 23, 2007*

**Physics**

There is no displacement in the direction of the force. work=force * displacement in the direction of the force.

*October 23, 2007*

**Precalculus with trigonometry**

Convert the 50.4 km/h to cm/s. Find the circumference of the 70cm diameter wheel. Use the above values to find revolutions/second. Multiply that by (2)(pi) to find radians/sec.

*October 23, 2007*

**Algerbra**

W=width L=length given: L = W + 5 Maximum of 180 feet of fencing is available So, 2L + 2W <= 180 Substitute the value for L and solve.

*October 23, 2007*

**physics**

(a) Recall that: Kinetic energy = (1/2)(m)(v^2) Your formula for kinetic energy is not correct.

*October 21, 2007*

**Algebra**

It looks OK.

*October 21, 2007*

**physics HELPPP please**

You add the forces, but since the force is in opposite directions, they will have different signs. So the result is that you effectively subtract them. The net force will be in the direction of the larger force. The resulting sign of adding two forces just indicates the ...

*October 21, 2007*

**Physic please check**

Two items to check: 1. Recall that the light beam strikes the mirror halfway up the mirror. 2. Check which sides/lengths are used to find tan(theta).

*October 20, 2007*

**Math**

You have the right idea, but made an error early. P=2L+2W, this is correct L=2W-14, this is given So, substituting... P=2*(2W-14) + 2W Solve this for W. Plug the value for W back into the second equation above to find L.

*October 18, 2007*

**Physics please help!**

Find the speed of light for the laser. How much distance error does 0.19 * 10^-9 represent? Find how far the laser light travels in this time to find the error.

*October 14, 2007*

**Physics**

Your first two answers look OK. 3rd question: Assuming that all momentum is conserved, the total momentum after the collision is the same as before the collision. The bowling ball is at rest, so no momentum there. The putty has a momentum of 1kg * 1m/s=1kg*m/s. After the ...

*October 14, 2007*

**Algebra problem - set up done - quick guidance**

You are on the right track. The problem states that the company has 36 male employees. I think you intended to say x=60 FEMALE employees. Now you know the number of male employees and the number of female employees. Add the 2 numbers to get the total employees.

*October 11, 2007*

**Calculus - need help!**

Ooops! the step before the limit statement should have read: 4x + 2deltaX + 1

*October 11, 2007*

**Calculus - need help!**

You started correctly, but you must have a math error in the intermediate steps. ((2(x+deltaX)^2 + (x+deltaX) - 1) - (2x^2 + x - 1) )/deltaX =((2x2+4(x*deltaX) + 2deltaX^2 + x + deltaX - 1) - (2x^2 + x - 1) ) /deltaX =(4(x*deltaX) + 2*deltaX^2 + deltaX)/deltaX =4x + deltaX + 1...

*October 11, 2007*

**math**

Find a nice common denominator. Multiplying the denominators from the different fractions will always work. In this case, 3 * 8 = 24. Convert 6 2/3 to some number over 24. Hint: 6 2/3 = 160/24 Convert 3 1/8 to some number over 24. Write a fraction where the new 6 2/3 value is ...

*October 10, 2007*

**math**

let x=Bill's age, y=Ted's age Bill is two years older than Ted. This gives the first equation: y=x-2 In 5 years, their ages will be: Bill=(x+5), Ted=(y+5) and... 4*Bill's age=5*Ted's age 4*(x+5)=5*(y+5) Use the first equation to substitute for y in the second ...

*October 10, 2007*

**Algebra**

Yes, this might be easier to understand if you think of expressing the perfect square as a product of its square roots. Rearrange to see that the product is a perfect square if x and y are perfect squares: x = a * a y = b * b x * y = a * a * b * b x * y = (a * b) * (a * b) let...

*October 10, 2007*

**Physics**

You can combine some of the constant acceleration equations to get one that does not have time: (final velocity)^2 = (initial velocity)^2 + (2 * a * s) where: a=acceleration, s=distance

*October 10, 2007*

**Physics**

Yes, you use the jump height to find the initial velocity of the jump. Then,you can use the equation you have shown with the the result, x, being set to 15.4cm. Solve for t. This will give the time in the bottom 15.4cm for the upward motion. The player will also spend the same...

*October 10, 2007*

**Physics**

If the velocity is constant, as given, then there is no net acceleration and so no net force. That eliminates two answers.

*October 10, 2007*

**science**

Assuming the car has no kinetic energy at the top... energy at the bottom = energy at the top energy at the bottom = kinetic energy kinetic energy = (1/2) * m * (v^2) So, (1/2)*m*(v^2)=20,000J Solve for v

*October 9, 2007*

**science**

For 60.0 Joules of work force * distance=work force=mass * acceleration (m * a) * distance=work 2kg * g * distance=60.0J substitute the gravitational acceleration for g and solve for distance.

*October 9, 2007*

**physics--HELP**

The velocity is the initial velocity + any velocity based on the acceleration of gravity. Gravity is a negative acceleration to an object thrown upwards. The minimum velocity will be where the ball stops going up and falls back down. Where maximum speed occurs will depend on ...

*October 9, 2007*

**trigonometry**

for the problem: sin(x) * cos(x) = 0 What values of x will result in cos(x)=0 or sin(x)=0? Hint: in the domain of 0<=x<(2*pi), there are 4 values.

*October 9, 2007*

**Physics**

Yes, solve for t for x=15.4cm. For starting at the top, the players initial velocity is 0. So the first term drops out. The calculated time is one half of the total time. Remember that for constant acceleration the time going up is the same as the time going down.

*October 9, 2007*

**Physics**

If you dropped an object, how long does it take for it to travel 15.4cm? Double this time to account for both the rising and falling motion.

*October 9, 2007*

**Math**

Let x=number of pigs Let y=number of chickens There are two equations with these two unknowns. Assume that the animals have the normal number of heads and feet for their species. Number of heads: x + y = 27 Number of feet: 4 * x + 2 * y = 78 Sove this equation set for x and y...

*October 8, 2007*

**Physics- for Quidditch**

The nice part of the problem is that it states that the rain outside of your apartment is straight down. So, this vector only has a y component. From the problem, it is probably OK to assume that L is driving on a flat highway. So, the vector from the car motion only has an x ...

*October 7, 2007*

**physics**

Be sure to take care of units conversions. From L's point of reference, the rain has the x component from her driving plus the y component of the rain falling. Find the resultant vector.

*October 7, 2007*

**physics**

First I would suggest converting mph to feet/second for both riders. When the second rider passes you, the first rider has been riding for 10 seconds past you. Find that distance (10 seconds * first rider's speed in feet/second). The second rider is catching up to the ...

*October 7, 2007*

**math**

For exponential notation: You want to express the number as a value greater or equal to 1 and less than 10 multiplied by a power of 10 Examples: 102.4 = 1.024 * 10^(2) 0.00343 = 3.43 * 10^(-3) 17,434 = 1.7434 * 10^(4) So, 20,500 = ?

*October 7, 2007*

**...Physics...**

You have two velocity vectors that you want to add. For this case, you might want to think of the x axis as the east/west line and the y axis as the north/south line. The jet is moving at 500 km/h due east. There is no y component, just the x component which is 500km/h. The ...

*October 7, 2007*

**algebra 3**

The domain is the possible values for r. These are given as -1,0,1,2 Using the given equation h(r) = 5r The range is the set of results for a given range. For this case, here are the first two. Domain Range -1 -5 0 0

*October 7, 2007*

**math**

I believe you have it. You said he paid $120. That is correct. You said he spent $140. I think you meant to say he received $140.

*October 7, 2007*

**math**

Add all the money the farmer paid for the horse. Add all the money the farmer got from selling the horse. Did he spend more than he got?

*October 7, 2007*

**algebra**

for x= -4 x^2 is not 8

*October 5, 2007*

**math**

I am guessing that the choice is fractions or decimals. Decimals are easier to see the difference,Suppose one fish is 7 13/16 and the other fish is 7 3/4. Quck! Which is longer?

*October 4, 2007*

**math**

Area of the rectangle is length * width. Aread of the triangle is 1/2 base * height. The length and width are given. Multiply them to find the area. Take that area to the triangle formula. Area = 1/2 base * height. The base is given. The only unknown is the height. That is ...

*October 4, 2007*

**Physics**

the velocity when the ball first contacts the floor is: V1 = sqrt(2*g*s) V1= sqrt(2 * 9.8(m/s^s) * 1.8m) The velocity when the ball just leaves (rebounds) works the same way except for the distance sign V2 = sqrt(2 * 9.8(m/s^2) * (-1.06m)) V1 - V2= delta V (you will be ...

*October 4, 2007*

**Physics**

Determine the velocity just as the ball makes first contact with the floor. Determine the velocity as the ball just just leaves the floor. Calculate the delta velocity. Divide this by the delta t to get (delta v)/((delta t) which is average acceleration. Look for the forumula ...

*October 4, 2007*

**Calculus**

If you want the derivative of the equation you have shown, you should look at the product rule for derivatives. Break this into two functions.

*October 4, 2007*

**Physics**

the formula that helps is: distance = v * t + (1/2)(a *t^2). Where a=acceleration, v=initial velocity, and t=time. Be very mindful of the sign for acceleration.

*October 4, 2007*

**Physics**

It might help to sketch a picture. The rope is at an angle of 36 degrees. It is usually important to know the x and y (horizontal and vertical) vectors from the 36 degree force in the rope. The x (horizontal) component is parallel to the ice and the old faithful f=ma can be ...

*October 4, 2007*

**Algenra**

There are times where they do not factor nicely. A quick check is to calculate the sqrt(b^2 - (4*a*c)) part of the quadratic equation. Here it looks like that would be sqrt(28) or 2*sqrt(7). This pretty much says it is not easily factored by inspection. Use the complete ...

*October 3, 2007*

**Algebra**

Sometimes it helps to get rid of those pesky fractions. Try multiplying both sides by 12 and then working the problem. If you multiply everything on both sides of an equals by the same value it will not change the value of the variable you are trying to find.

*October 3, 2007*

**algebra**

Remember to add or subtract terms to get all terms on one side of the equals and zero in the other side. Then, plug the coeffecients into the quadratic equation.

*October 3, 2007*

**Physics**

Objects can have an acceleration, but not be moving. When you are standing still, you are still experiencing the acceleration of gravity. C is not correct

*October 3, 2007*

**Physics**

Recall force = mass * acceleration

*October 3, 2007*

**Calculus?**

starting hint: 2 + what = 3?

*October 3, 2007*

**Physics**

You are thinking correctly. Delta v over delta t expresses acceleration. delta v = 78kts (nautical miles/second) (convert to other units if desired. delta t = 29.8s average acceleration = (78/29.8) nautical miles/sec^2.

*October 3, 2007*

**physics**

Go back and look at what you wrote. You are on the right path. You already know the value of d. It is 6m. You should not have put the value in for a, the acceleration. That is what you are trying to find. 6m = (1/2) * (a)* (1.9s)^2 Solve for a

*October 3, 2007*

**Calculus - Derivatives**

Check your work above. There is an error in the value on the left side. Fix that before the next step.

*October 3, 2007*

**Calculus - Derivatives**

exactly the same multiply the the coeffecient by exponent and subtract one from the exponent. -200 P ^-3

*October 3, 2007*