# Posts by bobpursley

Total # Posts: 44,556

**Writing**

I am uncertain what you want here with this writing. comments: a. It has a lot of grammatical errors b. To me, it seems disjointed and lacks development of thought. I am unsure of even the basic storyline. c. The closing seems far from connected to the first few paragraphs, ...

**math**

I agree with Ms Sue, you did a sloppy job of proofing if done at all.

**math**

I think you have two cones, same top, same shape, one ending at the top, the other ending at the bottom. You have the ratio of radii and the difference in volumes. The difference in heights of the two cones is 14cm. volumetop=1/3 PI*r^2(h) volumebottom=1/3 pi(2r)^2(h+14) no ...

**physics**

E=sigma/epsilion sigma is charge/m^2

**science**

https://www.youtube.com/watch?v=l5CYNs7ze6U

**Science**

falling stone: hf=49-4.9t^2 rising stone: hf=0+40t-4.9t^2 set the equations equal (hf=hf), and solve for time t, then put that t into either of the original equations and solve for hf.

**Science**

heat=Lf*mass 37E6*370=Lf*mass so use heat of vaporization Lf in J/kg

**College PHYsics**

a: no resistance, vf=g*t change speed to m/s vf=1357.64km/hr*1hr/3600sec*1000m/1km vf=377.1 m/s t= 377.1/9.8=38 seconds with no air resistance <how long did it actually take to reach the speed?> avg speed= distance/time=38.96km/259sec=150m/s so you can figure the average...

**Physics**

k=300N/.05m=6000 N/m work done= PEmax-PEmin = 1/2 k (.12^2-.10^2)

**maths**

It appears you are answer grazing, value.

**College Physics**

a. acceleration is due to gravity, g in the downward direction b. the velocity caught.. vcaught^2=voriginal^2 -2*g*heightabove solve for vcaught. c. avg velociy= (vorig+vfinal)/2 time=distance/avgvelocity

**physics**

looks like 3mS, and 4mE displacement= 5m

**Science**

average speed in block= 10m/s time to go .1 m n block= .1/10m/s=.01sec force*time= changemomentum and change in momentum is massbullet*20m/s so you need mass bullet

**Physics**

No name: ARe you looking for answers to turn in and don't wnat your teacher to know? That is rather gutless. hf=hi+vi*t+1/2 g t^2 0=80+12m/s*t-4.9t^2 solve for time t, with the use of the quadratic equation. Speed: Initial PE+initial KE= finalKE mg*80+1/2 m 12^2 = 1/2 m vf...

**Inverse Functions**

ThetaElevation= arcTan(362/550)

**Math**

geomea sqrt(sqrt(2*8))=2

**Chemistry**

a. find the energy of the 190nm photon, you have the right formula. Now subtract the threshold energy (E=h f). With the remainder, you have ke. b. correct, use E=1/2 m v^2 c. correct formula...

**physic**

I agree with Scott, the specific heat of water is 4.18Kj/Kg (or aboaut 4.2kg/kg so that heat would be 4.2kg/kg*2kg*75, that then is added to the heat of fusion (melting).

**Phy**

Look at this ... https://www.physicsforums.com/threads/magnetic-field-of-rotating-sphere.482886/

**Science (physics)**

acceleration= changevelociyt/time=28/4 m/s^2 distance: avg speed=14m/s, time is 4 seconds disistance=avgspeed*time

**Physics 2**

add the following heats: heat to change ice at -10 to 0C heat to melt ice at 0C heat to heat water from 0C to 20C

**Physics 2**

the sume of heats is zero... Heat to heat water + heat or condense steam+heat to cool steam=0 200*cw*(50-20)+Hv*m + m*Cw*(50-100)=0 solve for mass m.

**Physics**

index=speed light in vacumn/speedLightInMaterial what is 3/1.8?

**Kabir**

Use your name if you intend to post here.

**chemestry**

CaBr2(aq)+2AuClO4(aq) ? 2AuBr(s)+Ca(ClO4)2(aq)

**science**

yes, my eyes are failing.

**science**

Wonder who would offer that as a "sample"? Molarity: grams/molmass*volumeInLiters so if you had one liter of this stuff, you so assume 1 liter of this stuff, which is 1100g .15*1100/98*1=165/98 Moles/liter Normality= 2*molarity Molality=.15*1100/98*1.1

**chemistry**

PV=nRT n/V=P /RT n/V; but n=mass/molmass*volume, so density/molmass=n/V n/V=density/molmass then molmass=density*RT/Pressure put in NTP, and you have it.

**chemistry**

grams of anacid= .17(volumestomach)*molmassAnacid

**Physics 1**

Is this what you want to calculate? 10*sin(2*35)*1/9.81 Lets look: time in air: hf=hi+vi*sin35*t-4.9t^2 t(10*sin35deg - 4.9t)=0 timeinair= 10sin35/9.8 now, horizontal distance: distance=10cos35*timeinair distance=10*cos35*10*sin35/9.81 = 100cos35deg*sin35deg *1/9.81 which is ...

**Physics**

vf^2=vi^2+2ad 0=6^2+2*(-2)d solve for distance d. how long? avg speed * time= distance 3 m/s * time=d time= d/3

**Time rates**

from the triangle: 20^2=h^2 + x^2 h is vertical height, and x is distance base. take the derivative... 0=2h dh/dt + 2x dx/dt dh/dt=-dx/dt x/h = 1 * 4/h where h= sqrt(400-16)

**Science**

http://www.askiitians.com/iit-jee-structure-of-atom-and-nucleus/solved-examples-of-structure-of-atom/ see problem 1.

**Physics 11**

all correct

**Physics**

ball1: h=200-4.8t^2 ball2: h=40*t-4.8t^2 subtract the equations. 0=200-40t t= 5 seconds where? h=200-4.8*5^2

**Physics 11**

draw a ray diagram to confirm your work.

**Physics**

There are several good explanations/demonstrations here: https://www.youtube.com/watch?v=8PcWjxuIs9o

**Chemistry**

Good.

**Research Methodology and Program Evaluation**

relating to the scientific description of peoples and cultures with their customs, habits, and mutual differences... Women qualify as subjects for ethnographic study. Ethnographic study: relating to the scientific description of peoples and cultures with their customs, habits...

**Physics**

hf=hi+vi*t-1/2 g t^2 hf=hi=0 t(vi-gt/2)=0 t=0 t=2vi/g t= 2*120/50=you do it.

**Algebra 1**

-1/(2xy^3)^5 -1/(32x^5y^15) C is correct.

**Algebra 2**

think not on B.

**math**

Whatever the market will bare. Most would think the annual divided by 12 months....In reality, it is more than that.

**Physics**

Ok, I am visulizing two inclines back to back, with a pulley at the top, and masses on each side. on each block, the gravity component DOWN the plane is mg*cos35 No resistive force (friction). so first, find the motion. Net force=(14-5)*9.8*cos35 twoward the greater mass. net ...

**Physics**

Don: I don't think the mass leaves nor goes below the surface because of weight and the surface is hard, so the only acceleration can be horizontal, no component downward. If the tension were greater, it could have went upward.

**Physics**

1183*cos40=106*acceleration your teacher is too easy, should have added friction.

**Science**

is there some particular reaction you have in mind?

**Physics**

Upi meed aor density, density of air is 1.20 kg/m^3 The net lift per wing area, using the Bernoulli equation, is (1/2)(air density)[(Vtop)^2-(Vbottom)^2] = ...... So that is lift per m^2, and you have 50m^2

**Physics**

the bouyant force depends on water displaced. The buoyant force on the wood is equal to the mass of the wood. The aluminum is denser than the wood, lets say 4 times. volume of aluminum=1/4 volume of wood. Lets pretend the wood has .6 volume submerged, so the volume of aluminum...

**Physics**

force=mass*v^2/r so the thrusters stop movement in the original direction, and recreate it in the perpendicular direction. workdone=1/2 mv^2 + 1/2 mv^2=mv^2 work done E=force*distance = mv^2/r * r+ mv^2/r *r=2mv^2 E/T=4 check my thinking

**Physics**

It matters what the angles are.

**math**

Hmmmmmm

**College Chemistry**

heat=masswater*c*deltatemp = 86.3g*4.184J/gC*(31.8-17.4) of course, this assumes you know the density of water to be 1g/ml

**Physics**

x=force/k so if you increse force by 2x, stretch will be 2x, or 5cm*2=10cm

**Science**

ghost host+g

**math**

Lord, it is a rate problem Rate problem: quantity=rate*time calories=320cal/hr * timeinhours

**physics**

time to fall h meters h=1/2 g t^2 or t= sqrt(2h/g) now, time to traverse that distance horizontally in time t. s=v*t solve for v but v^2=2*d*a1 or s= sqrt(2d*a1)*sqrt(2h/g) s=sqrt(2d*a1*2h/g) check my thinking

**physics**

http://www.jiskha.com/display.cgi?id=1497452479

**physics**

https://www.quora.com/If-the-wire-of-resistance-is-stretched-to-the-double-of-the-length-then-new-resistance-will-be-what

**Physics**

it point will accelerate, or the point will push back with an equal or opposite force.

**physics**

What is 3/5 * 200N ?

**physics**

number=current/e where e is the charge per electron speed: 1/2 mv^2=20E3*e m is mass of electron solve for v

**Physics**

total energy=max pe 1/2 m 14^2+m*g*29=mgh solve for max height h

**physics**

see other post

**Physics**

heat=power*time mc*deltaTemp=power*time 1.5kg*c*80C=1.5j/hr*timeinhours so you need c in Joules/kgC and solve for time in hours.

**phy**

a. time to fall: h=1/2 g t^2 t= sqrt(2h/g)=you do it horizontal distance: timetoFall*1.70 b. t=time above * sqrt(1/12) horizontal distance=1/12*origwideth*v solve for v. you did not give the original sidewalk width.

**algebra 1**

You need to be specific on the problem you are stuck on. We have no idea what your unit 6 includes.

**Math Explain**

put the terms in normal order: 18x^2 + 6 + 4x - 15x^2 - 4 + 13x 18x^2 - 15x^2 + 13x + 4x +6-4 now combine like terms 3x^2 +17x + 2 Unless you made a sign error, I dont agree with what you "know" is the answer.

**Jiskha**

It reminded me of Sunday Church, and the devil himself giving a sermon. I didn't remove it, but thought on it. Our site is not for chat about schools (including cheating at Connections). We try to help students with concepts, not supply answers. We are not for cheating, ...

**Physics 11**

Yes, if the friction involved in attaining different speeds was the same....in real life, it is not. Friction of air is dependent on velocity squared as a rule of thumb.

**Physics 11**

No, the work done was the difference in kinetic energies, assuming the work to overcome friction at each speed was constant.

**Physics 11**

the net force on the ball is only from gravity, mg. Remember, even half way upwards, it is still accelerating downward due to the force of gravity.

**physics**

1/2 m v^2 * .8=mcDeltaTemp DeltaTemp=.4*180^2/128 notice mass of the bullet divides out, so no change of units is needed for specific heat.

**physics**

I agree, law of cosines is the way to go.

**chemistry: Plumpycat**

Plumpy. This only works if you treat each side as absolute values. The better way to work this is to realize the SUM of the heats gained is zero (one gains, one loses). mc ?T (copper) + mc ?T (water) =0 That way, the math works perfectly.

**Math**

it is half way between 0 and 8.

**Physical science**

blood can be filtered, or centifruged, separating its components. Concrete is not a heterogenous mixture: look at the pebbles in it. Milk has fat that floats to the top.

**Physics**

This is a bit tricky. air resistance is indeed dependent on velocity squared. initial KE=final height- friction work 1/2 m 7^2=mgh - friction friction losses: during falling, F=ma=m(dv/dt) but we know F=mg-kv^2 or m(dv/dt)=mg-kv^2 so now you have a differential equation in v. ...

**Electives**

I have a degree in such: It came out of the operational analysis field in the 1960s, then moved to be called systems analysis (Univ of S. Calif), and part of that study is the interface of humans and organizations on systems to get things done. One of the better seminars I ...

**science 7b tecca**

Usually, it is cycling of stress as occurs in seasonal freezing.

**science**

subtracting the bottle mass water=50g X=30 g so the density of the liquid X is 30/50 times the density of water.

**physics**

http://www.cpp.edu/~skboddeker/131/131hw/ch12h.htm

**Physics**

work=PENew-PEold = kqq/.12-kqq/.06 q is the charge on each of the charges or qq=50E-12 Of course, you could also realize the distance is being halved, so work=2kqq/.12

**social studies**

Is it possible you did not look at the picture?

**Physics**

Assume on rebound they have the following velocities: large ball: V, in upward direction small ball: V, in downward direction you can calculate V from the height of the drop. Assume conservation of momentum, and if needed, conservation of energy. Momentum MV-mV=M*0+mV' V&#...

**Physics**

WEight=21kg/m^2 * 9.8N/kg*(.09m)^2

**math**

What is the quadratic equation?

**Science**

4H2O (g)+3Fe(s)>>>Fe3O4(s) +2 H2(g)

**Chemistry**

alocohol is easy toevaporate, however, its sturcture (helping attache itself two water molecules) allows the water there to go with it.

**physics**

See example 3. https://books.google.com/books?id=BukDAAAAMBAJ&pg=PA1433&lpg=PA1433&dq=a+simple+pendulum+has+a+period+of+2.0s+and+magnitude+of+swing+5cm.find+i-the+velocity+of+the+bob+ii-the+acceleration+of+the+bob&source=bl&ots=gDxmNuClKx&sig=agV4IL0lNHcEuDWK8urzpBYLHkA&hl=en&...

**physics**

Yes, the the final temp will be larger, due to the lost absorbance capacity of the water in the calorimeter.

**science**

sea water glass air

**Non**

I don't know about race, but in this fast-paced information age, one can get dumb and dumber by not reading current literature. It takes effort and work to stay ahead.

**Math**

and the told riddle of moving to the door, 1/2 way, the 1/4 way, then 1/8 way...does she ever reach the door?

**Pre-Calculus 12**

2 is log100 log 3^4+ log100 log(100*3^4) log (ab)=loga + log b

**Engineering Systems**

Or, besides lever or screw, one can use hydraulic force (see Pascal's principle)

**PHYSICS**

What is 10*cos30?

**science**

Nonsense is rampant.

**Physics**

??? what do you mean "base of center"? Flux thru what surface?

**Chemistry**

What compound are you thinking of?