# Posts by Hannah

Total # Posts: 3,341

**Chemistry**

A watch is to be electroplated with gold. - provide a solution that would make a suitable electrolyte for this cell. I'm not quite sure how to figure out what the electrolyte solution is made of. Any help you can give me would be wonderful!

**Chemistry**

A watch is to be electroplated with gold. - provide a solution that would make a suitable electrolyte for this cell. This is the only question I'm having a little trouble with. I'm not quite sure how to figure out what the electrolyte solution is made of. Any help you ...

**Science, Chemistry**

What is the volume of 75.65 grams of zinc

**chem**

Cobalt-60 is a strong gamma emitter that has a half-life of 5.26 yr. The cobalt-60 in a radiotherapy unit must be replaced when its radioactivity falls to 75% of the original sample. If an original sample was purchased in October 2005, when will it be necessary to replace the ...

**Chemistry**

The density of alcohol is 0.80 grams per milliliter. What is the specific gravity of alcohol?

**Math**

What is the difference between the measured values of 1.05m and 1.050m? What factor of a measurement tool determines the sig figs of a measured value? The two values are different because of their sig figs, the first has 3 and the other has 4. I think that the factor of a ...

**Physics(Please check)**

Please diregard. I found my mistake.

**Physics(Please check)**

An experiment was done where a tiny steel ball was measured with a micrometer. I know I already posted a question about this before and was given a respond but after trying to fix my answers I am still lost. If someone could please review my results and tell me where I went ...

**Physics(Please check)**

What is the difference between the measured values of 1.05m and 1.050m? What factor of a measurement tool determines the sig figs of a measured value? The two values are different because of their sig figs, the first has 3 and the other has 4. I think that the factor of a ...

**Physics(Please check)**

What is the difference between the measured values of 1.05m and 1.050m? What factor of a measurement tool determines the sig figs of a measured value? The two values are different because of their sig figs, the first has 3 and the other has 4. I think that the factor of a ...

**Physics(Please help, thanks)**

Please disregard. I found my mistake.

**Physics(Please help, thanks)**

An experiment was done where a tiny steel ball was measured with a micrometer. I know I already posted a question about this before and was given a respond but after trying to fix my answers I am still lost. If someone could please review my results and tell me where I went ...

**Physics(Please help, thank you)**

I had to do an experiment where a tiny steel ball was measured using a micrometer. There was then a series of calculations that needed to be completed and then a percent error had to be calculated. I think that my data may be incorrect or maybe I am just not doing the ...

**algr.2**

solve for the equation or formula for the specified variable x+y-a=b,for y over Z

**Math(Please help, thank you)**

Yes my data is probably wrong I'm just not sure where I messed up

**Math(Please help, thank you)**

Oh ok so now to find the percent error do I subtract 120,000 from 7800 and then multiply by 100?

**Math(Please help, thank you)**

I am trying to calculate my percent error for an experiment conducted. I need to compare my average density calculated to the accepted average density but I am having trouble doing this because of the conversions. My average density was 0.12 g/mm^3. The accepted value is for ...

**chem**

As the mass of the particle is increased while the speed of the particles remains the same, would you expect the bending to increase, decrease, or stay the same? i thought it would increase because of the weight pulling it. but it was wrong

**Physics**

suppose the force exerted by the air on one face of a cube is 8820 N.each side of the cube measure 30 cm. calculate the pressure on this face.?

**Chemistry**

i have no idea how to set this problem up! please help! A 22.19-g sample of a solid is placed in a flask. Toluene, in which the solid is insoluble, is added to the flask so that the total volume of solid and liquid together is 50.0 mL. The solid and toluene together weigh 47....

**chemistry/math**

nevermind! i converted wrong!

**chemistry/math**

The density of air at ordinary atmospheric pressure and 25°C is 1.19 g/L. What is the mass, in kilograms, of the air in a room that measures 12.0 ft 12.5 ft 7.3 ft? i made ft^3 into Liters and got 8,346,211.799 then I made the grams into kilograms and set up density = mass...

**DR BOB PLEASE HELP CHEM**

there are no instructions... i don't see it

**DR BOB PLEASE HELP CHEM**

Consider the reduction of 4-t-butylcyclohexanone. If the procedure calls for 153 mg of 4-t-butylcyclohexanone, what mass of sodium borohydride should be added?

**CHEMISTRY**

thanks :] it is correct. D and C are the answers

**CHEMISTRY**

In TLC, why do you spot multiple times? Select one or more correct answers. A. To fill the capillary almost instantly by capillary action. B. So the developing chamber solvent does not evaporate. C. The higher compound concentration facilitates visualization. D. To acheive a ...

**Chemistry**

Consider the reduction of 4-t-butylcyclohexanone. If the procedure calls for 153 mg of 4-t-butylcyclohexanone, what mass of sodium borohydride should be added?

**chemistry**

There is more than one answer for this problem.

**chemistry**

In TLC, why do you spot multiple times? Select one or more correct answers. A. To fill the capillary almost instantly by capillary action. B. So the developing chamber solvent does not evaporate. C. The higher compound concentration facilitates visualization. D. To acheive a ...

**Chem**

Consider the reduction of 4-t-butylcyclohexanone. If the procedure calls for 153 mg of 4-t-butylcyclohexanone, what mass of sodium borohydride should be added?

**chem**

oh oops i didn't see the e3

**chem**

I am confused so the answer would be .87?

**chem**

-879.6?

**chem**

do this using the appropriate number of sig figs 320.44 − (3104.1/2.6) i got -880 as my answer and it said to check my sig figs. I thought it was all the numbers up to the ones place

**Chem**

Indicate which of the following are exact numbers. the mass of a stapler? i think its inexact because all staplers are different sizes. Is that correct? Also,the mass of a postage stamp. is that inexact? because they can also be diff. sizes?

**sig figs**

I am having trouble with my sig figs Many scientific data are reported at 25°C. What is this temperature in kelvins and in degrees Fahrenheit? I got 3.0e2 degrees kelvin since it will have to have two sig figs but it said it was wrong

**english-grammar**

I am writing an essay and am not sure If I should combine these two sentences with a semi colon or just leave them separate. Please help! (It may take...will be fruitful) I have found that nothing can be accomplished without hard work. It may take a large amount of persistence...

**Chemistry**

Awesome, thank you so much!!

**Chemistry**

Suggest a procedure that could be used to remove lead (II) ions from industrial waste water as a precipitate. Provide an equation and explain your choice.

**math**

Find the error. Sam is finding 9-6+2. Find his mistake and correct it. Steps: First solve the problem. Second, write a summary statement. Third, find Sam's mistake and explain in complete sentences.

**Chemistry**

Describe what hard water is and how a water softening unit works. Provide balanced chemical equations to show how sodium sulphate can remove these ions (Magnesium and Calcium). The first was no problem, but I am having trouble trying to get through the second part balancing ...

**Math applied/pre-cal**

(-8/5)^7/4*(-8/5)^1/4=64/25 Not sure how get this answer . Could please show me the steps.

**Physics(Please help)**

The two strings have the same tension and mass per unit length, but they differ in length by 0.54 cm. The waves on the shorter string propagate with a speed of 41.7 m/s, and the fundamental frequency of the shorter string is 227 Hz. Determine the beat frequency produced by the...

**Physics(Please check)**

A gas, while expanding under isobaric conditions, does 660 J of work. The pressure of the gas is 1.40 x 105 Pa, and its initial volume is 1.70 x 10-3 m3. What is the final volume of the gas? Would I multiply the two values? W = p*dV = p(Vf - Vi)--for isbaric p is constant. ...

**Physics(Please respond)**

A system does 210 J of work on its environment and gains 80.6 J of heat in the process. Find the change in the internal energy of (a) the system and (b) the environment. ÄU = Q - W Where ÄU is the change in the internal energy of the system, Q is the heat/energy ...

**Physics(Please respond)**

A system does 210 J of work on its environment and gains 80.6 J of heat in the process. Find the change in the internal energy of (a) the system and (b) the environment. Physics(Please respond) - Elena, Thursday, June 21, 2012 at 2:33am ÄU = Q - W Where ÄU is the ...

**Physics(Please help)**

A gas, while expanding under isobaric conditions, does 660 J of work. The pressure of the gas is 1.40 x 105 Pa, and its initial volume is 1.70 x 10-3 m3. What is the final volume of the gas? Would I multiply the two values?

**Physics(Please help)**

What is the smallest number of whole logs (ñ = 725 kg/m3, radius = 0.0800 m, length = 3.60 m) that can be used to build a raft that will carry four people, each of whom has a mass of 60.0 kg? I do not know how to start this.

**Physics(Please check)**

A paperweight, when weighed in air, has a weight of W = 6.95 N. When completely immersed in water, however, it has a weight of Win water = 4.26 N. Find the volume of the paperweight. Would I multiply the two values of weight and then by the density of water? 4.26=weightinair-...

**Physics(Please help)**

so I would do log of 4.83 then times 10?

**Physics(Please help)**

The intensity (in W/m2) of one sound is 4.83 times as great as the intensity of another sound. Relative to the quieter sound, what is the intensity level â of the louder sound? I am not sure how to start this. Thank you.

**Trig**

5/2

**Physics(Please respond)**

A satellite has a mass of kg orbits the Earth in a circular path with radius 1.0e^7m. What is the period of the satellite? I think I already posted this but I am still confused. My teacher said to use T= 2(pi)r^3/2 / sqrt GmE So I just plugged the numbers in T= 2(pi)(1.oe^7)^3...

**Physics(Please check, thanks)**

Looking through my textbook I found what it was that my teacher said to use. R= Vo^2 Sin 2Q / g So I guess I just have to plug in the numbers; Vo is 25^2 and Q is 40. Correct?

**Physics(Please check, thanks)**

Where did you get 625 and 4.9?

**Physics(Please check, thanks)**

A football player kicks a ball with a speed of 25m/s at an angle of 40 degrees relative to the horizontal. Ignore air resistance. 1) What is the ball's range? R= V0^2 sin Q / g Is this the correct equation to use?

**Physics(Please, please respond)**

so would it be between 90 and 180 or 180 and 270?

**Physics(Please, please respond)**

Vector A has a magnitude of 3.0 m and direction 1o3 degrees relative to the positive x-axis. Vector B has magnitude 5.0m and direction 215 relative to the positive x-axis. For the resultant I did Rx= 3 cos 103 + 5 cos 215 Ry=3 sin 103 + 5 sin 215 Then sqrt Rx^2 + Ry^2 and got ...

**Physics(Please respond)**

A source emits sound uniformly in all directions. There are no reflections of the sound. At a distance of 12 m from the source, the intensity of the sound is 1.7 × 10-3 W/m2. What is the total sound power P emitted by the source? Would I do 1.7e^-3 (12) ?

**Physics(Please help)**

A paperweight, when weighed in air, has a weight of W = 6.95 N. When completely immersed in water, however, it has a weight of Win water = 4.26 N. Find the volume of the paperweight. Would I multiply the two values of weight and then by the density of water?

**Physics(Please help)**

An object is inside a room that has a constant temperature of 295 K. Via radiation, the object emits three times as much power as it absorbs from the room. What is the temperature (in kelvins) of the object? Assume that the temperature of the object remains constant. I thought...

**Physics(Please help)**

A 0.0979-m x 0.215-m x 0.260-m block is suspended from a wire and is completely under water. What buoyant force acts on the block? Would I multiply all the numbers?

**Physics(Please respond)**

An object is solid throughout. When the object is completely submerged in ethyl alcohol, its apparent weight is 15.8 N. When completely submerged in water, its apparent weight is 13.0 N. What is the volume of the object? Would I start by doing 15.8 - 13?

**Physics(Please respond)**

A system does 210 J of work on its environment and gains 80.6 J of heat in the process. Find the change in the internal energy of (a) the system and (b) the environment. I am not sure how to start this. Thank you for the help.

**Physics**

Blood flows through a section of a horizontal artery that is partially blocked by a deposit along the artery wall. As a hemoglobin molecule moves from the narrow region into the wider region, its speed changes from v2 = 0.800 m/s to v1 = 0.422 m/s. What is the change in ...

**Physics(Please respond)**

A system does 210 J of work on its environment and gains 80.6 J of heat in the process. Find the change in the internal energy of (a) the system and (b) the environment. I am not sure how to start this.

**Physics(Please help)**

How did you get 6.378e^6 for R?

**Physics(Please help)**

A satellite of mass 500kg orbits the Earth in a circular path with radius 1.0e^7 m . 1) What is the period of the satellite? I know that the equation is T= 2(pi)r^3/2 / sqrt GmE mE = 5.98e^24 does G = 6.67e^-11 ??

**Physics(please check)**

No it is sin^-1 (1.15/9.8)

**Physics(please check)**

Solve for Q Q= sin^-1 1.5/9.8 I got 8.80 Is this correct? I have a TI-30 calculator and to do the sin^-1 I pushed the 2nd button and then sin. I am not sure if this is correct.

**physics(Please check)**

Actually I think that the direction would be between 180 and 270 degrees since the R is bigger than A but less than B. Would you agree?

**physics(Please check)**

so for the direction of the resultant R would it be between 90 and 180 degrees?

**physics(Please check)**

Vector A has a magnitude of 3.0 m and direction 1o3 degrees relative to the positive x-axis. Vector B has magnitude 5.0m and direction 215 relative to the positive x-axis. 1) The resultant R=A + B has magnitude? I did Rx= 3 cos 103 + 5 cos 215 Ry=3 sin 103 + 5 sin 215 Then ...

**Child day care management**

determine the nature of the need for child care facilities in your community.

**Physics(Please respond)**

There is a rod that is split into two sections. The left side is copper with value of 390, temp of 100 degrees c and the length is 2m. The right side is silver, 420, temp 20 degrees celsuis, and length 1m. I need to calculate the temperature. 390 X 1 X 100-t / 2 = 420 X 1 X t-...

**Physics(Please check)**

Please please respond

**Physics(Please check)**

There is a PV diagram with ABC and the cycle is moving clockwise. segment AB is isobaric BC is isochronic AC cannot be determined The delta U for this is zero and the W=positive. The last questions asks if the heat flow Q is positive, negative, or zero and the answer given is ...

**Physics(Please check)**

There is a rod that is split into two sections. The left side is copper with value of 390, temp of 100 degrees c and the length is 2m. The right side is silver, 420, temp 20 degrees celsuis, and length 1m. I need to calculate the temperature. 390 X 1 X 100-t / 2 = 420 X 1 X t-...

**Physics(Please respond)**

thank you!

**Physics(Please respond)**

A 0.33-kg metal sphere oscillates at the end of a vertical spring. As the spring stretches from 0.12 to 0.26 m (relative to its unstrained length), the speed of the sphere decreases from 5.3 to 4.2 m/s. What is the spring constant of the spring? I know that the formula is F=-...

**Physics(Please, please check)**

A uniform horizontal beam is attached to a vertical wall by a frictionless hinge and supported from below at an angle è = 38o by a brace that is attached to a pin. The beam has a weight of 347 N. Three additional forces keep the beam in equilibrium. The brace applies a...

**Physics(Please help)**

A uniform horizontal beam is attached to a vertical wall by a frictionless hinge and supported from below at an angle è = 38o by a brace that is attached to a pin. The beam has a weight of 347 N. Three additional forces keep the beam in equilibrium. The brace applies a...

**Physics(please check)**

A spring stretches by 0.0226 m when a 4.39-kg object is suspended from its end. How much mass should be attached to this spring so that its frequency of vibration is f = 7.35 Hz? 7.35 = 0.0226(4.39x) Did I set this up correctly?

**Physics(Please check)**

A spring stretches by 0.0226 m when a 4.39-kg object is suspended from its end. How much mass should be attached to this spring so that its frequency of vibration is f = 7.35 Hz? 7.35 = 0.0226(4.39x) Did I set this up correctly?

**Phsyics(Please respond)**

A uniform horizontal beam is attached to a vertical wall by a frictionless hinge and supported from below at an angle è = 38o by a brace that is attached to a pin. The beam has a weight of 347 N. Three additional forces keep the beam in equilibrium. The brace applies a...

**Physics(Please help)**

Some bacteria are propelled by motors that spin hair-like flagella. A typical bacterial motor turning at a constant angular velocity has a radius of 1.9x10-8m, and a tangential speed at the rim of 2.7x10-5 m/s. (a) What is the angular speed (the magnitude of the angular ...

**Physics(Please check)**

A uniform plank of length 5.0 m and weight 225 N rests horizontally on two supports, with 1.1 m of the plank hanging over the right support (see the drawing). To what distance x can a person who weighs 404 N walk on the overhanging part of the plank before it just begins to ...

**Physics(Please respond)**

Some bacteria are propelled by motors that spin hair-like flagella. A typical bacterial motor turning at a constant angular velocity has a radius of 1.9x10-8m, and a tangential speed at the rim of 2.7x10-5 m/s. (a) What is the angular speed (the magnitude of the angular ...

**Physics(Please help)**

A dentist causes the bit of a high-speed drill to accelerate from an angular speed of 1.44 x 104 rad/s to an angular speed of 5.05 x 104 rad/s. In the process, the bit turns through 1.77 x 104 rad. Assuming a constant angular acceleration, how long would it take the bit to ...

**Derivatives ~ Calculus**

If dy/dx = (1 + x)/(xy), x>0, and y=-4 when x=1, then when x=3, y= what?

**Physics(Please check)**

A rectangular plate is rotating with a constant angular speed about an axis that passes perpendicularly through one corner, as the drawing shows. The centripetal acceleration measured at corner A is n times as great as that measured at corner B. What is the ratio L1/L2 of the ...

**Physics(Please help)**

A fan blade is rotating with a constant angular acceleration of +12.4 rad/s2. At what point on the blade, as measured from the axis of rotation, does the magnitude of the tangential acceleration equal that of the acceleration due to gravity? I do not know how to start this.

**Physics(Please help)**

A person is riding a bicycle, and its wheels have an angular velocity of 26.0 rad/s. Then, the brakes are applied and the bike is brought to a uniform stop. During braking, the angular displacement of each wheel is 17.6 revolutions. (a) How much time does it take for the bike ...

**Physics(Please check)**

After 14.6 s, a spinning roulette wheel has slowed down to an angular velocity of 1.22 rad/s. During this time, the wheel has an angular acceleration of -4.51 rad/s2. Determine the angular displacement of the wheel. I did w0= wf + (4.51)(14.6) = 1.22+45.1 46.32(14.6) - (1/2)(4...

**Physics(Please help)**

Three forces act on a hockey puck as it slides across the ice, and it is in equilibrium. The force F is applied at the center and has a magnitude of 25 N. The force F1 is applied at the top edge, and F2 is applied half way between the center and the bottom edge. Find the ...

**Physics(please check)**

thank you, now I understand what I did wrong.

**Physics(please check)**

A 53-N crate is suspended from the left end of a plank. The plank weighs 21 N, but it is not uniform, so its center of gravity does not lie halfway between the two ends. The system is balanced by a support that is 0.30 m from the left end of the plank. How far to the right of ...

**Physics(Please respond)**

so first I have to do equation 2? So 2*pi*17.6 = I am not sure what wo is. Would it be the 26.0?

**Physics(Please respond)**

A person is riding a bicycle, and its wheels have an angular velocity of 26.0 rad/s. Then, the brakes are applied and the bike is brought to a uniform stop. During braking, the angular displacement of each wheel is 17.6 revolutions. (a) How much time does it take for the bike ...

**Physics(Please help)**

Please disregard.