Recent content by pebbles

So, if Jimmy adds a resistor in parallel to a circuit with two other resistors... Homework Statement wouldn't the resistance decrease? Homework Equations The Attempt at a Solution

Homework Statement A 75.0 W bulb is connected to a 120 V source. A lamp dimmer puts a resistance in series with the bulb. What resistance would be needed to reduce the current to .300 A? Homework Equations R=V/I The Attempt at a Solution R=120/.3A=400 ohms. The answer is 210...

Homework Statement A force of .053 N is required to move a charge of 37 microCoulombs a distance of .25m in an electric field. What is the size of the electric potential difference between the two points? Homework Equations ? The Attempt at a Solution I'm really stuck...

oh i see! 10^-17/10^-19=100 so therefore 2.5*10^2. thanks so much! :D

uhh, I'm confused....?

Homework Statement How many excess electrons are on a ball with a charge of -4.00*10^-17 C? Homework Equations I know that the charge per electron is 1.60 *10^-19C. The Attempt at a Solution My textbook does not explain how to do this, but I thought I would divide-->4.00*10^-17...

Homework Statement Once closed organ pipe has a length of 3.2 m. Frequency of the note played by this pipe is 27 Hz. When a second pipe is played at the same time, a 1.50 Hz beat note is heard. By how much is the second pipe too long? Homework Equations ? The Attempt at a Solution...

Homework Statement Which is more efficient, or has the highest lm/W, a lower- or higher-power light bulb? To find out, look at bulbs and record the power and lumens. Homework Equations Lumen, lm, = P or luminous flux. The Attempt at a Solution Power of the light bulbs would be...

OHHH! oops, .25 kg! Ok, so I get 3.0 X10^2s. Close enough I suppose. Thanks so much for your help blochwave and hallsofivy. I appreciate it.

Something is wrong; I did 300 J/s * t (seconds to get 8.9X10^5 Joules)=8.9 X10^5 J Divided both sides by 300 J and got 3.0 X 10^3 seconds; the answer is 3.7 X10^2 s.

4180 J/Kg*K(specific heat of h2o given in book) boiling point of h2o=373 K, so need to raise temp 85 K. Not sure what number of kg i need to multiply by; mass of cup or mass of h20. I did mass of h2o-->4180 J/kg*K * 2.5 kg * 85 K=8.9 X 10^5 J. Right so far? I don't know how to determine...

Homework Statement A 3.00 X 10^2 W electric immersion heater is used to heat a cup of water. The cup is made up of glass and its mass is 3.00 X10^2 g. It has 250 g of water at 15 degrees celsius. How much time is needed to bring water to boiling point. Assume no heat is lost and temp of cup is...

I think you'd use 60.0 N. 15.0N is just the mass in kg times gravity.

Dick, actually, it's not 25N, that was a typo. Question is actually 30 N. so, Ff=30N--> coefficient of kinetic friction=30 N/12.0 kg * 9.80 m/s^2= .26. Am I right? I thank everyone for their input. :]

well, wait Ffriction=muK*m*g. would it just be 12 kg * 9.8 m/s^2?