Saturday

October 25, 2014

October 25, 2014

Total # Posts: 1,169

**physics**

If the electric field near a proton is 9.00 x 10^-3 N/C, what is the distance from the proton?
*July 12, 2014*

**chemistry**

explain whether using solid sodium hydroxide pellets rather than aqueous sodium hydroxide would alter the enthalpy
*July 11, 2014*

**chemistry**

Why would you have to subtract the heat capacity of the calorimeter when calculating the heat of the reaction?
*July 11, 2014*

**chemistry**

Why would you have to subtract the heat capacity of the calorimeter when calculating the heat of the reaction?
*July 11, 2014*

**Physics**

all electric field lines start on positive charges. explain why this makes sense.
*July 10, 2014*

**physics**

What is a charge dipole a basic model of? would it be a magnet?
*July 10, 2014*

**Physics- help please**

A beta particle (fast moving electron) is released by a nuclear decay and starts travelling at 1.5x10^6 m/s [NΘE] in the Earth's magnetic field which has a value of 3.0x10^-5 T. If the force experienced by the beta particle is 4.34x10^-18 N, determine the angle ...
*July 10, 2014*

**Physics**

Two parallel wires are carrying current. If the currents are in the same direction, what is the interaction between the two wires and why? How would this be different in the currents were in opposite directions?
*July 9, 2014*

**Physics help**

1. if the magnetic field is 2.1 m from a current carrying wire is 7.1x10^-5 T, what is the current flowing through the wire? 2. The electromagnet in an MRI has a magnetic field of 2.5 T. If there are 100 A of current running through the magnet, how many turns are there in a 1....
*July 9, 2014*

**Physics**

1. You are looking into a current carrying solenoid and notice that the compass needle indicates that you are at the south end of the magnetic field. What is the direction of the current in the coil and how do you know? Would it be clockwise because current moves towards the ...
*July 8, 2014*

**Physics- check answer please**

1. A 15 kg boy falls out of his bed at a height of 0.50 m. What is the amount of gravitational potential energy lost by the boy? my answer: 74 J 2. What is the speed of a 0.25 kg ball if its kinetic energy is 15 J? my answer: 11 m/s 3. if the speed of an object is tripled and ...
*July 4, 2014*

**Physics**

a child throws a ball in a net where it gets stuck. Does the motion of this ball defy the law of conservation of momentum? explain
*July 4, 2014*

**physics word problem**

A 60.0 kg girl stands up on a stationary floating raft and decides to go into shore. She dives off the 180 kg floating raft with a velocity of 4.0 m/s [W]. Ignore the substantial friction real objects in water experience. What is the speed of the raft just after the girl dives?
*July 4, 2014*

**physics**

How would I answer number 3? 1. A sumo wrestler originally jumps 10 cm above a trampoline but has the same total energy of a small ball that was 200 cm higher than the trampoline. What causes this equivalency? 2. If a 40 kg gymnast and a 400 kg sumo wrestler each dropped from ...
*July 3, 2014*

**Physics**

A sumo wrestler originally jumps 10 cm above a trampoline but has the same total energy of a small ball that was 200 cm higher than the trampoline. What causes this equivalency?
*July 3, 2014*

**Physics -- check answers please**

Use g=10 N/kg in this assignment. 1. What is the gravitational energy (relative to the unstretched surface of the trampoline) of the 20 kg ball at its apex 2 m above the trampoline? I got 400 J 2. What is the kinetic energy of the ball just before impacting the trampoline? I ...
*July 3, 2014*

**Check answers please?**

Use g=10 N/kg in this assignment. 1. What is the gravitational energy (relative to the unstretched surface of the trampoline) of the 20 kg ball at its apex 2 m above the trampoline? I got 400 J 2. What is the kinetic energy of the ball just before impacting the trampoline? I ...
*July 3, 2014*

**Physics**

fill in the blank ( Energy and momentum unit) 1. the work done to stretch a spring is not equal to the to force multiplied by displacement because force is ____ as the spring stretches 2. A child goes down a slide at the playground, gaining speed as she goes. Her momentum ____...
*July 3, 2014*

**Physics- check answer please**

I am supposed to fill in the blanks without a word bank. 1. I you push a crate with 40 N of force at an angle of 30 degrees and your friend pushes with a force of 40 N horizontally, the amount of work you are doing is _____ the amount of work your friend is doing on the crate ...
*July 2, 2014*

**Physics**

Which of the following is an inertial frame of reference? a) a child on a moving swing observes the child next to them moving in sync b) a child on a moving swing observes a ball that they throw to their parents standing on the ground c) a child observes the motion of the ...
*July 1, 2014*

**physics**

1. what happens to the force required for an object to maintain circular motion if the period is halved (goes twice as fast around the circle)? a) force doubles b) force quadruples c) force is halved d) force is quartered 2. In a pulley problem involving an inclined plane: a) ...
*July 1, 2014*

**physics**

1. the applied force on a stationary object is less than the maximum force of static friction. Which of the statements are false a) the object will move backwards b) the actual force of static friction will be equal to the applied force c) the object will remain stationary ...
*June 28, 2014*

**Physics**

In projectile motion, how would you find the final velocity of the object just before it hits the ground a) find the second vertical velocity b) add the final and horizontal velocities directly c)add the final and horizontal velocities as vectors d) add the final and ...
*June 28, 2014*

**Physics help**

how might life be different if static friction did not exist? give three examples and reference formulas to support your answers I have three examples but I do not understand what the questions mean by reference formulas
*June 27, 2014*

**Physics multiple choice**

1. What happens to the force required for an object to maintain circular motion if the period is halved (goes around twice as fast around the circle)? a) force doubles b) force quadruples c) force is halved d) force is quartered my answer: c 2. Which is true a) the ...
*June 27, 2014*

**Physics**

1. A ball is launched from a cliff with an initial velcity of 10 m/s at an angle of 40 degrees above horizontal. If the ball lands 24 m away, determine the height of the cliff. 2. if the mass A is 1 kg and the mass of B is 6.0 kg, determine the acceleration of the system and ...
*June 27, 2014*

**Physics**

how might life be different if static friction did not exist? give three examples and reference formulas to support your answers I have three examples but I do not understand what the questions mean by reference formulas
*June 26, 2014*

**Physics**

I got 25 m/s for #2 but I still do not know how to answer #1 and #3
*June 26, 2014*

**Physics**

1. A ball is launched from a cliff with an initial velcity of 10 m/s at an angle of 40 degrees above horizontal. If the ball lands 24 m away, determine the height of the cliff. 2. if the mass A is 1 kg and the mass of B is 6.0 kg, determine the acceleration of the system and ...
*June 26, 2014*

**Physics**

1. What happens to the force required for an object to maintain circular motion if the period is halved (goes around twice as fast around the circle)? a) force doubles b) force quadruples c) force is halved d) force is quartered my answer: c 2. Which is true a) the ...
*June 26, 2014*

**math word problems**

A room is a square with integer dimensions. it is made 3 feet wider and 2 feet deeper. the increase in area is 46 square feed. What were the dimensions of the old room?
*June 4, 2014*

**chemistry**

What is the monomer and polymer structure of DNA?
*May 23, 2014*

**Calculus**

Consider the function f (x) = 2x^3 - 3x^2 - 72x + 7 Find and classify the critical points. Identify the intervals of increase and decrease, and state the intervals of concavity.
*May 22, 2014*

**Physics**

what is the role of a commutator in a DC motor?
*May 21, 2014*

**Physics -- check answers please**

The earth's magnetic field a) is slightly off centre compared to the Earth's rotational axis of rotation b) has its magnetic south pole at the geographic north pole c) attracts the north end of the compass needle to the geographic north pole d) all of the above Would ...
*May 21, 2014*

**Physics**

The earth's magnetic field a) is slightly off centre compared to the Earth's rotational axis of rotation b) has its magnetic south pole at the geographic north pole c) attracts the north end of the compass needle to the geographic north pole d) all of the above 2. A ...
*May 20, 2014*

**Calculus Reply**

The only info I have is when the container is half full which is 500mL in 32.7 seconds and quarter full is 250mL in 23.8 seconds.
*May 20, 2014*

**Calculus **

I did an experiment where I had to measure how fast water flowed out of a container at different times and with different volumes (from 0mL-1000mL in increments of 50). I also had to record the values into a table and graph them. (I got an exponential function). I got a slope ...
*May 20, 2014*

**Calculus**

Thanks! It is an exponential graph
*May 20, 2014*

**Calculus**

I have a data table and I graphed the data. I have to find the slope of a tangent at t=0. Would the slope just be zero?
*May 20, 2014*

**Calculus**

I did an experiment where I had to measure how fast water flowed out of a container at different times and with different volumes. I also had to record the values into a table and graph them. (I got an exponential function). I am to answer the following questions and I do not ...
*May 20, 2014*

**Calculus- answer check**

A brand new stock is also called an initial public offering. This model predicts the percent overvaluation of a stock as R(t)=9t((t-3)^3/2.718) where is the overvaluation in percent and t is the time in months after the initial issue. Use the information provided by the first ...
*May 19, 2014*

**derivative**

Would the first derivative of R(t)=9t[(t-4)^3/2.718] be R'(t)=3.311258278(3(t-4)^2(t)+(t-4)^3) and the second derivative be R''(t)=3.311258278(6(t-4)x+6(t-4)^2)?
*May 18, 2014*

**average and instantaneous rate of change**

what is the difference between an average rate of water flow and an instantaneous rate of water flow?
*May 18, 2014*

**Calculus**

Sorry about that. It looks like thins: R(t)= 9t[(t-4)^3/2.718] The 9t is on the outside without a denominator
*May 17, 2014*

**Calculus**

A brand new stock is also called an initial public offering. In this model, the period immediately after the stock is issued offers excess returns on the stock—that is, the stock is selling for more than it is really worth. One such model predicts the percent ...
*May 17, 2014*

**Calculus**

thanks! Would the first derivative be R'(t)=3.311258278(3(t-4)^2(t)+(t-4)^3) and the second derivative be R''(t)=3.311258278(6(t-4)x+6(t-4)^2)
*May 17, 2014*

**Calculus**

A brand new stock is also called an initial public offering. In this model, the period immediately after the stock is issued offers excess returns on the stock—that is, the stock is selling for more than it is really worth. One such model predicts the percent ...
*May 17, 2014*

**Calculus**

determine f" if f(x)=sqrt(x^3+2)
*May 16, 2014*

**Calculus**

If f(x1)>f(x2) for every x1>x2 then what is the behaviour of f(x)?
*May 16, 2014*

**Calculus**

If f(x1)>f(x2) for every x1>x2, then what is the behaviour of f(x)? I believe that the answer is that f(x) is increasing but I do not know how to show my work for that
*May 15, 2014*

**Calculus**

I figured out the answer!
*May 15, 2014*

**Calculus**

A movie theater wants to determine the price per ticket that should be charged in order to maximize its revenue. The theater can accommodate 2000 movie goers per night, but the average attendance is about 1400 people per night. The average ticket price is about $8.00. Market ...
*May 15, 2014*

**physics- answers check**

5. A magnetic field map shows a. the direction of the magnetic field. b. a few representational field lines. c. relative strength of the magnetic field. d. All of these choices are correct. my answer: d 6. Magnetic field lines a. can cross each other when the field is strong. ...
*May 10, 2014*

**physics- answers check**

1. For a bar magnet, the magnetic field lines point a. towards the South pole. b. towards the North pole. c. always towards the magnet. d. always away from the magnet. my answer: a 2. Magnetic field lines a. are straight lines. b. are always circles. c. form continuous loops. ...
*May 10, 2014*

**Physics**

1. A 40Ω , 20Ω and 60Ω resistor is connected in a parallel circuit. Which resistor would have the greatest current passing through it and why? 2. A 24Ω , 8Ω and 60Ω resistor is connected in a series circuit. Which resistor would have the greatest ...
*May 8, 2014*

**Physics question**

Does the crest of a wave usually have a larger amplitude than the trough?
*May 4, 2014*

**Physics**

A vibrating point on a spring travels 60 mm during three cycles. What is the amplitude of the vibration?
*May 4, 2014*

**Physics- check answer please**

1. A vibrating point on a spring travels 60 mm during three cycles. What is the amplitude of the vibration? a) 0.05 mm b) 5.0 mm c) 15.mm d) 20.mm e) 180 mm my answer: I got 10 mm but it is not listed as an option
*May 2, 2014*

**Physics**

When a tuning fork of unknown frequency is sounded simultaneously with a 512 Hz tuning fork, 20 beats are heard in 4.0 seconds. What are the possible frequencies of the unknown tuning fork?
*May 2, 2014*

**Physics waves**

1. A vibrating point on a spring travels 60 mm during three cycles. What is the amplitude of the vibration? a) 0.05 mm b) 5.0 mm c) 15.mm d) 20.mm e) 180 mm my answer: I got 10 mm but it is not listed as an option 2. When a tuning fork of unknown frequency is sounded ...
*May 1, 2014*

**Physics waves**

1. A vibrating point on a spring travels 60 mm during three cycles. What is the amplitude of the vibration? a) 0.05 mm b) 5.0 mm c) 15.mm d) 20.mm e) 180 mm my answer: I got 10 mm but it is not listed as an option 2. When a tuning fork of unknown frequency is sounded ...
*April 30, 2014*

**Physics waves- check answers please**

1. A vibrating point on a spring travels 60 mm during three cycles. What is the amplitude of the vibration? my answer: I got 10 mm but I'm not sure if it is the correct answer. 2. For two connect pendulums to resonate, they must have the same: a) mass b) amplitude c) ...
*April 28, 2014*

**Physics waves- check answers please**

1. A vibrating point on a spring travels 60 mm during three cycles. What is the amplitude of the vibration? my answer: I got 10 mm but I'm not sure if it is the correct answer. 2. For two connect pendulums to resonate, they must have the same: a) mass b) amplitude c) ...
*April 27, 2014*

**Physics waves- check answers please**

1. A vibrating point on a spring travels 60 mm during three cycles. What is the amplitude of the vibration? my answer: I got 10 mm but I'm not sure if it is the correct answer. 2. For two connect pendulums to resonate, they must have the same: a) mass b) amplitude c) ...
*April 27, 2014*

**Math**

A microscopic worm is eating its way around the inside of a spherical apple of radium 6 cm. What is the probability that the worm is with 1 cm if the surface of the apple? (Hint: V=(4/3)Pir^3)
*April 24, 2014*

**Math**

According to a publisher's records, 20% of the books published break even, 30% lose $1000, 25% lose $10,000, and 25% earn $20,000. When a book is published, what is the expected income for the book?
*April 24, 2014*

**Math**

A bag of chocolate candies has the following colors: 5 yellow, 7 green, 8 red, 5 orange, and 4 brown. What is the probability of getting two of the same color when pouring two out of the bag? a. Describe a simulation that could be used to answer the preceding question.
*April 24, 2014*

**Physics waves- help please**

A police officer with good ears hears an approaching motorcycle. The engine sound he eats as the bike approached is 195 Hz. a) Is the actual sound the bike makes higher or lower in pitch? b) After the bike passes he hears 147 Hz as the perceived pitch. If it was a nice 20 ...
*April 22, 2014*

**Physics waves**

thanks in advanced! A guitar emits a 440 Hz tone. How far apart are the crests in room temperature air (20 degrees celsius)? How long does it take the string to vibrate from crest position to trough position (across twice the amplitude)?
*April 22, 2014*

**Physics waves- check answer please**

I would like to know if my answer is correct. Thanks in advanced! A person with their head sideways in the water sees a beaver slap its tail on the lake surface 1.2 km away. What is the time difference between the sound heard in the ear listening in the air and the ear hearing...
*April 22, 2014*

**Physics waves- check answer please**

I would like to know if my answer is correct. Thanks in advanced! A person with their head sideways in the water sees a beaver slap its tail on the lake surface 1.2 km away. What is the time difference between the sound heard in the ear listening in the air and the ear hearing...
*April 21, 2014*

**Physics waves- help please**

1. A person is listening to a new instrument capable of sounds ranging from 10 dB to 150 dB and with frequencies from 12 Hz to 30,000 Hz. Comment on the suitability of this instrument for the musician or audience. 2. A guitar emits a 440 Hz tone. How far apart are the crests ...
*April 21, 2014*

**Physics waves- check answers please**

thanks again!
*April 21, 2014*

**Physics waves- check answers please**

I am not too sure if my answers are correct. Here are the questions: 1. A student standing near a brick wall claps her hands and hears the echo 0.250 s later. If the speed of sound was 340.0 m/s, how far from the wall was she? For this question I got 85 m. 2. How much faster ...
*April 21, 2014*

**Physics waves- check answers please**

thanks a lot!
*April 21, 2014*

**Physics waves- check answers please**

1. In a standing wave, the medium at the tip of a loop is a) showing destructive interference b) not moving c) at the original amplitude of the wave d) showing constructive interference my answer: b 2. If a motorcycle is travelling toward an observer the frequency the observer...
*April 21, 2014*

**Physics waves- check answers please**

1. In a standing wave, the medium at the tip of a loop is a) showing destructive interference b) not moving c) at the original amplitude of the wave d) showing constructive interference my answer: b 2. If a motorcycle is travelling toward an observer the frequency the observer...
*April 21, 2014*

**Physics waves**

I am stuck with both of these questions. Thanks in advanced! 1. If one tone has a frequency of 110 Hz and another tone is played near it with a tone of 113 Hz, the beat frequency is ___ Hz 2. A standing wave has 3 nodes in a string 20 m long. The wavelength of this wave is __ ...
*April 20, 2014*

**Physics waves- check answers please**

thanks a lot!
*April 20, 2014*

**Physics waves- check answers please**

1. If a bat emits 10 sounds in 5 seconds, what is the frequency of the bat's vocal outbursts (rounded to first decimal place) My answer: 2.0 Hz 2.If one crest has a 3 cm amplitude and interacts with another pulse to produce a crest 8 cm high this demonstration" a) ...
*April 20, 2014*

**free-body diagram help**

A 20.0 kg block is being pushed forward on a flat surface with a force of magnitude 45.0 N against a frictional force of 13.0 N To draw this free-body diagram, would I only have the forces mentioned in the question? or would i include the -9.8m/s^2 force of gravity? Also, how ...
*April 13, 2014*

**Energy question**

Your friend comes across a good deal to purchase a gold ring. She asks you for advice for you to test the ring. The ring has a mass of 4.54 g. When you heat the ring with 94.8 J of energy, its temperature rises from 23.0 degrees celsius to 47.5 degrees celsius. Would you ...
*April 12, 2014*

**Energy question**

how could you determine the efficiency with which the mechanical energy of a pendulum is conserved?
*April 12, 2014*

**word problem**

If equal amounts of heat are added to equal masses of silver and copper, both at the same initial temperature, which will reach the higher final temperature? Explain your answer. The specific heat capacity of silver is 0.235 J/g degree Celsius and that of copper is 0.385 J/g ...
*April 12, 2014*

**Energy question**

thanks a lot! you gave me some good ideas! and i agree with you about the fluorescent light bulbs. They don't last as long as the box says
*April 12, 2014*

**Energy question**

How would a $10.00 compact fluorescent light bulb (15 W) be an overall money saver compared to an incandescent light bulb (60 W) that costs $0.50?
*April 12, 2014*

**Energy multiple choice question**

Which of the following samples has the highest specific heat capacity? a) A 100 kg sample of lead requires 13 000 J to increase its temperature by 1 K b) A 50 g sample of water releases 1050 J as it cools by 5 degree Celsius c) A 2 kg sample of copper receives 2340 J of ...
*April 12, 2014*

**Physics Energy**

How would a $10.00 compact fluorescent light bulb (15 W) be an overall money saver compared to an incandescent light bulb (60 W) that costs $0.50?
*April 11, 2014*

**physics**

Show that the acceleration is 7.5 m/s2 for a ball that starts from rest and rolls down a ramp and gains a speed of 30 m/s in 4 s
*April 9, 2014*

**chemistry**

Sodium metal adopts a body-centered cubic structure with a density of 0.97g/cm3. A. Use this information and Avogadro's number to estimate the atomic radius of sodium. B. If it didn't react so vigorously, sodium could float on water. Use the answer from part a to ...
*April 3, 2014*

**english**

May you please edit this essay? Holden Caulfield in “Catcher in the Rye”, seems to be obsessed with mortality and youthful innocence, both of which are embodied in James Castle and Allie Caulfield. Holden demonstrates these infatuations in his conversation with ...
*March 10, 2014*

**chemistry**

how to calculate the amount of heat in calories absorbed when 50.0 g of water at 20 degrees C spreads over your skin and warms the body temperature, 37 degrees C
*March 1, 2014*

**Physics**

A ball is fastened to one end of a 30cm string, and the other end is held fixed to a support. the ball whirls in a horizontal circle. Find the speed of the ball in its circular path if the string makes an angle of 30 degrees to the vertical.
*February 27, 2014*

**chemistry**

A room contains 48 kg of air. How many KWh of energy are necessary to heat the air in the house from 7oC to 28oC? The heat capacity of air is 1.03 J/goC
*February 22, 2014*

**Differential Equations**

Solve dy/dx = y/(2y-x) using rational substitution (using v=y/x) with the initial condition y(0)=1. I solved this problem and found C (the constant) to be undefined. That is not the correct answer.
*February 15, 2014*

**Physics**

Ohhh I see what I did wrong! Thanks a lot again!
*February 3, 2014*

**Physics**

I was wondering if my answers are correct. 1. A 50kg person is taking a ride on an elevator travelling up at a steady speed of 2.5m/s. Find the time fo the elevator trip if the elevator does 4900 J of work on the person. My answer: First I used the formula f=mg to find the ...
*February 3, 2014*

**Physics**

thanks a lot!
*February 3, 2014*

**Physics**

I was wondering if my answers are correct. Thanks in advance. 1. A boy pushes down on a car rolling horizontally down the road. The boy pushes down vertically with 10N of force as the car rolls 3.0m horizontally. What work is done? my answer: 30 N•m (or would it be -30N&#...
*February 3, 2014*

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