Wednesday

April 1, 2015

April 1, 2015

Total # Posts: 20

**physics (please help)**

Four 20 ohm resistors are connected in parallel and the combination is connected to a 20 V emf device. The current in any one of the resistors is: A) 0.25 A B) 1.0 A C) 4.0 A D) 5.0 A E) 100 A I get B V=IR I= 20V/20 ohms = 1 A for any one of the resistors thank you correct.
*March 28, 2007*

**physics question**

The sum of the emfs and potential difference around a closed loop equals zero" is a consequence of: a) Newton's third law b) Ohm's law c) Newton's second law d) conservation of energy e) conservation of charge For this question: I had picked d conservation of ...
*March 28, 2007*

**please check (physics)**

Current flows out of a 110V source through a 10 ohm resistor and then through parallel branches, one containing a 20 ohm resistor and the other a 30 ohm resistor. Find V I R P V I R P 50 5 10 250 60 3 20 180 60 2 30 120 _____________________________ 110 5 22 550 First R total...
*March 28, 2007*

**physics (please check)**

Four 20-ohm resistors are connected in series and the combination is connected to a 20 V emf device. The current in any one of the resistors is: A) .25 A B) 1.0 A c) 4.0 A D) 5.0 A E) 100 A My answer: A R= 20 + 20 + 20 + 20 =80 V= IR 20/80=I I=.25 A battery with an emf of 24 V...
*March 28, 2007*

**physics (please check)**

A total resistance of 3 ohms is to be producd by combining an unknown resistor R with a 12 ohm resistor. What is the value of R and how is it connected to the 12 ohm resistor a) 4.0 ohm parallel b) 4.0 ohm in series c) 2.4 ohm in parallel d) 2.4 in series e) 9.0 in parallel My...
*March 28, 2007*

**physics**

The emf of a battery is equal to its terminal potential difference: A) under all conditions B) only when the battery is being charged C) only when a large current is in the battery D) only when there is no curent in the battery E) under no conditions my answer: d, The chemical...
*March 27, 2007*

**physics (thanks)**

in the context of the loop and junctions rules for electrical circuits a junction is: a) where a wire is connected to a resistor b) where a wire is connected to a battery c) where only two wire are joined d) where three or more wire are joined e) where a wire is bent My answer...
*March 27, 2007*

**physics**

For any circuit the number of independent equations containing emfs, resistances, and currents equals the number of branches. why? The only type of circuit that branches is parallel. But there can be electric circuit with a combination of both parallel and series. Thank you ...
*March 15, 2007*

**Physics**

Thanks for any help :) Four 20 ohm resistors are connected in parallel and the combination is connected to a 20V emf device. The current is: A) 0.25A B) 1.0 A C) 4.0 A D) 5.0 A E) 100 E Parallel circuits: I know that the voltage is 20V and the Resistance is 20 V. So, I divided...
*March 15, 2007*

**physics**

During a lighting discharge, 30C of charge move through a potential difference of 1.0 X 10^8V in 2.0X10^-2s. The energy released by this lighting bolt is: a)1.5 X 10^11 J b) 3.0 X 10^9 J c) 6.0 X 10^7 J d) 3.3 X 10^6 J e) 1500 J Ok I am not really sure what equation to use for...
*March 12, 2007*

**Physics**

If 500 J of work are required to carry a charged particle between two points with a potential difference of 40V, the magnitude of the charge on the particle is: a) 0.040 C b) 12.5 C c) 20C D) cannot be computed unless the path is give e) none of these My solution: I used the ...
*March 12, 2007*

**Standing waves and resonance (physics)**

A nylon string has a linear density of 7.2g/m and is under a tension of 150N. The fixed supports are 90cm apart. The string is oscillating in the standing wave pattern. Find a)speed b)wavelength c) frequency v=sqr(F/u(linear density) v=sqrt(150N/7.2g/m) = 4.56m/s b) wavelength...
*February 6, 2007*

**waves (physics)**

Two sinussoidal waves identical except for phase travel in the same direction along a string and interfere to produce a resultant wave given by y(x,t)= (3.0mm) sin(20 rad/m)x - 4.0rad/s t + 0.820 rad) with x in meters and t in seconds. What is a) the wavelength of the two ...
*February 6, 2007*

**Physics (please help)**

A sinusoidal wave travels along a string. The time for a particle to move from maximum displacement to zero is 0.170s. What are the a)period b)frequency c) the wavelength is 1.40m what is the wave speed? ok I know i need the equation T=1/f and the wave equation y=YSIN{kx-wt...
*February 4, 2007*

**physics (check my work pleas)**

A 5.00kg ball is swung at the end of a 1.25 m chain with a w of 2.0s^-1. Find the balls a)V (m/s) b) KE 1/2mv^2 c) I, inertia d) Ke with I e) Fc--> centripetal force Work a) v=rw v= (1.25m)(2.0s^-1) v= 2.5 m/s b) 1/2 mv^2 (.5)(5)(2.5)^2 c) I=mr^2 = (5)(1.25)^2 = 15.6 d0 =.5...
*December 11, 2006*

**please check**

If a wheel turns with a costant rotational speed then: each point on its rim moves with constant roational velocity, each point on its rim moves with constant translational acceleration, the wheel turns with constant translation acceleration, the wheel turns through equal ...
*December 9, 2006*

**physics (please check work)**

Four identical particles, each with mass m, are arranged in the x,y plane like a cross. They are connected by light sticks to form a rigid body. If m=2.0kg and a=1.0 m the rotational inertia of this array about the y axis is: work: I know that I= mr^2 I=(2.0kg)(1.0m)^2 I=2 kgm...
*December 9, 2006*

**physics**

If a wheel turns with a costant rotational speed then: each point on its rim moves with constant roational velocity, each point on its rim moves with constant translational acceleration, the wheel turns with constant translation acceleration, the wheel turns through equal ...
*December 9, 2006*

**physics**

A 1-kg block is lifted vertically 1m by a boy. The work done by the boy would be one jule or would no work be done. I'm confused, I thought lifting wasn't considered work. The work done is actually about 9.81 joules. Think of gravity pulling on the block as an ...
*November 6, 2006*

**Physics (please check)**

A 6.0kg block is released from rest 80m above the ground. When it has fallen 60m its kinetic energy is: I got 1200J as my answer mgh=(6.0*9.81* 60m)=3531.6 PE + KE= (ME + KE) 3531.6 + KE= (6.0*9.81*80m) KE= 1177.2 is that right A 6.0 Kg block is thrown up from a point 20m ...
*November 5, 2006*

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