Tuesday
September 2, 2014

Posts by justin


Total # Posts: 756

physics
A physicist at a fireworks display times the lag between seeing an explosion and hearing its sound, and finds it to be 0.800 s. (a) How far away(m) is the explosion if air temperature is 22.0°C, neglecting the time taken for light to reach the physicist? (b) How much ...
July 31, 2013

physics
An 8 hour exposure to a sound level of 95.0 dB may cause hearing damage. What energy in joules falls on a 0.850 cm diameter eardrum so exposed?
July 31, 2013

physics
The amplitude of a sound wave is measured in terms of its maximum gauge pressure. By what factor does the amplitude of a sound wave increase if the sound level goes up by 38.0 dB?
July 31, 2013

physics
Henry, thank you for your help, but the answer is not correct.
July 31, 2013

physics
19 cars in a circle at a boom box competition produce a 130 dB sound level at the center of the circle. What is the average sound level(dB) produced there by each, assuming interference effects can be neglected?
July 31, 2013

physics
(a) By what factor is one sound more intense than another if the sound has a level 17.0 dB higher than the other? (b) If one sound has a level 32.0 dB less than another, what is the ratio of their intensities?
July 31, 2013

physics
A physicist at a fireworks display times the lag between seeing an explosion and hearing its sound, and finds it to be 0.800 s. (a) How far (m)away is the explosion if air temperature is 22.0°C, neglecting the time taken for light to reach the physicist? (b) How much ...
July 31, 2013

physics
Show that 60.0 L of gasoline originally at 15.0ºC will expand to 61.1 L when it warms to 35.0ºC, how much gasoline has spilled by the time they warm to 35.0ºC ?
July 30, 2013

physics
(a) A solar collector is 12.0% efficient in gathering solar energy and converting it to heat. If the average intensity of sunlight on one day is 700 W/m2, what area(m^2) should your collector have to gather energy at the rate of 150 W? (b) What is the maximum cost ($)of the ...
July 30, 2013

physics
What is the wavelength (m)of an earthquake that shakes you with a frequency of 11.5 Hz and gets to another city 85.0 km away in 12.0 s?
July 30, 2013

physics
How many times a minute does a boat bob up and down on ocean waves that have a wavelength of 43.0 m and a propagation speed of 5.25 m/s?
July 30, 2013

physics
When a pendulum with a period of 2.00000 s is moved to a new location from one where the acceleration of gravity was 9.80 m/s2, its new period becomes 1.99711 s. By how much does the acceleration of gravity differ at its new location? (m/s2)
July 28, 2013

physics
Two parakeets sit on a swing with their combined center of mass 15.0 cm below the pivot. At what frequency do they swing?
July 28, 2013

physics
Suppose a diving board with no one on it bounces up and down in a simple harmonic motion with a frequency of 3.00 Hz. The board has an effective mass of 10.0 kg. What is the frequency of the simple harmonic motion of a 62.0 kg diver on the board?
July 28, 2013

physics
When 1.60 multiplied by 105 J of heat enters a cherry pie initially at 20.0°C, its entropy increases by 470 J/K. What is its final temperature?
July 28, 2013

physics
Calculate the net work output of a heat engine following path ABCDA in Figure 14.30, where horizontal axis is V and each unit is 0.5*10^-3 m^3, V1 = 1.0*10^-3 m^3 and V2 = 4.0*10^-3 m^3. The vertical axis is P(N/m^2); A is (1.0*10^-3,2.6*10^6), B is (4.0*10^-3,2.0*10^6), C is...
July 28, 2013

physics
(a) How much heat (J) flows from 1.00 kg of water at 46.0°C when it is placed in contact with 1.00 kg of 18°C water in reaching equilibrium? (b) What is the change(J/K) in entropy due to this heat transfer? (c) How much work (J) is made unavailable, taking the lowest ...
July 28, 2013

physics
(a) What is the best coefficient of performance for a heat pump that has a hot reservoir temperature of 50.0°C and a cold reservoir temperature of -20.0°C? (b) How much heat in kilocalories would it pump into the warm environment if 3.60 multiplied by 107 J of work (10...
July 28, 2013

physics
When 1.60 multiplied by 105 J of heat enters a cherry pie initially at 20.0°C, its entropy increases by 470 J/K. What is its final temperature (C)? I use delta S = entropy change = 1.6*10^5*[1/293 - 1/T2] = 470 Solve for T2, but it's not correct. Please someone help me...
July 28, 2013

physics
(a) How much heat flows from 1.00 kg of water at 46.0°C when it is placed in contact with 1.00 kg of 18°C water in reaching equilibrium? (b) What is the change in entropy due to this heat transfer? (c) How much work is made unavailable, taking the lowest temperature to...
July 28, 2013

physics
When 1.60 multiplied by 105 J of heat enters a cherry pie initially at 20.0°C, its entropy increases by 470 J/K. What is its final temperature?
July 28, 2013

physics
0.460 kg mass suspended from a spring oscillates with a period of 1.50 s. How much mass must be added to change the period to 1.95 s?
July 28, 2013

physics
A 0.810 m long brass pendulum experiences a 18.0°C temperature increase. (a) Calculate the original period(s). (b) What is the change in the period(s)? (c) Find the ratio of the change in period to the original period, and calculate how long (h) a clock run by this ...
July 28, 2013

physics
A spring has a length of 0.190 m when a 0.300 kg mass hangs from it, and a length of 0.750 m when a 2.80 kg mass hangs from it. (a) What is the force constant of the spring? (b) What is the unloaded length(m) of the spring?
July 28, 2013

physics
(a) A bathroom scale has a spring that is compressed by 1.50 cm when a 165 kg person stands on the scale. Assuming the spring is described by Hooke's law, find its force constant. (b) How much would it be compressed if a 94.0 kg person stands on the scale in an elevator ...
July 28, 2013

physics
A spring has a length of 0.260 m when a 0.300 kg mass hangs from it, and a length of 0.750 m when a 1.90 kg mass hangs from it.(a) What is the force constant of the spring?(b) What is the unloaded length of the spring?
July 28, 2013

physics
While taking a plane flight to a meeting, a physicist decides to do a mental calculation of how much fuel the plane would consume in the absence of friction, assuming its engines have an efficiency of 22.0% and the mass of the plane is 200,000 kg. Each gallon of jet fuel ...
July 28, 2013

physics
(a) What is the best coefficient of performance for a heat pump that has a hot reservoir temperature of 50.0°C and a cold reservoir temperature of -20.0°C? (b) How much heat in kilocalories would it pump into the warm environment if 3.60 multiplied by 107 J of work (10...
July 28, 2013

physics
(a) How much heat (J) flows from 1.00 kg of water at 46.0°C when it is placed in contact with 1.00 kg of 18°C water in reaching equilibrium? (b) What is the change(J/K) in entropy due to this heat transfer? (c) How much work (J) is made unavailable, taking the lowest ...
July 28, 2013

physics
When 1.60 multiplied by 105 J of heat enters a cherry pie initially at 20.0°C, its entropy increases by 470 J/K. What is its final temperature (C)?
July 28, 2013

physics
Calculate the net work output of a heat engine following path ABCDA in Figure 14.30, where horizontal axis is V and each unit is 0.5*10^-3 m^3, V1 = 1.0*10^-3 m^3 and V2 = 4.0*10^-3 m^3. The vertical axis is P(N/m^2); A is (1.0*10^-3,2.6*10^6), B is (4.0*10^-3,2.0*10^6), C is...
July 28, 2013

physics
What is the unstretched length?
July 27, 2013

physics
A spring has a length of 0.190 m when a 0.300 kg mass hangs from it, and a length of 0.750 m when a 2.80 kg mass hangs from it. (a) What is the force constant of the spring? (b) What is the unloaded length of the spring?
July 27, 2013

physics
When 1.60 multiplied by 105 J of heat enters a cherry pie initially at 20.0°C, its entropy increases by 470 J/K. What is its final temperature (C)? Drwls answered: delta S = entropy change = 1.6*10^5*[1/293 - 1/T2] = 470 Solve for T2 But after I checked the answer, it is ...
July 26, 2013

physics
(a) How much heat (J) flows from 1.00 kg of water at 46.0°C when it is placed in contact with 1.00 kg of 18°C water in reaching equilibrium? (b) What is the change(J/K) in entropy due to this heat transfer? (c) How much work (J) is made unavailable, taking the lowest ...
July 26, 2013

physics
(a) What is the best coefficient of performance for a heat pump that has a hot reservoir temperature of 50.0°C and a cold reservoir temperature of -20.0°C? (b) How much heat in kilocalories would it pump into the warm environment if 3.60 multiplied by 107 J of work (10...
July 26, 2013

physics
While taking a plane flight to a meeting, a physicist decides to do a mental calculation of how much fuel the plane would consume in the absence of friction, assuming its engines have an efficiency of 22.0% and the mass of the plane is 200,000 kg. Each gallon of jet fuel ...
July 26, 2013

physics
Calculate the net work output of a heat engine following path ABCDA in Figure 14.30, where horizontal axis is V and each unit is 0.5*10^-3 m^3, V1 = 1.0*10^-3 m^3 and V2 = 4.0*10^-3 m^3. The vertical axis is P(N/m^2); A is (1.0*10^-3,2.6*10^6), B is (4.0*10^-3,2.0*10^6), C is...
July 26, 2013

physics
(a) How much heat (J) flows from 1.00 kg of water at 46.0°C when it is placed in contact with 1.00 kg of 18°C water in reaching equilibrium? (b) What is the change(J/K) in entropy due to this heat transfer? (c) How much work (J) is made unavailable, taking the lowest ...
July 25, 2013

physics
When 1.60 multiplied by 105 J of heat enters a cherry pie initially at 20.0°C, its entropy increases by 470 J/K. What is its final temperature (C)?
July 25, 2013

physics
(a) What is the best coefficient of performance for a heat pump that has a hot reservoir temperature of 50.0°C and a cold reservoir temperature of -20.0°C? (b) How much heat in kilocalories would it pump into the warm environment if 3.60 multiplied by 107 J of work (10...
July 25, 2013

physics
While taking a plane flight to a meeting, a physicist decides to do a mental calculation of how much fuel the plane would consume in the absence of friction, assuming its engines have an efficiency of 22.0% and the mass of the plane is 200,000 kg. Each gallon of jet fuel ...
July 25, 2013

physics
Calculate the net work output of a heat engine following path ABCDA in Figure 14.30, where horizontal axis is V and each unit is 0.5*10^-3 m^3, V1 = 1.0*10^-3 m^3 and V2 = 4.0*10^-3 m^3. The vertical axis is P(N/m^2); A is (1.0*10^-3,2.6*10^6), B is (4.0*10^-3,2.0*10^6), C is...
July 25, 2013

physics
(a) What is the magnitude of the average acceleration of a skier who, starting from rest, reaches a speed of 8.02 m/s when going down a slope for 4.28 s? (b) How far does the skier travel in this time?
July 25, 2013

physics
Concrete sidewalks are always laid in sections, with gaps between each section. For example, the drawing shows three identical 2.4-m sections, the outer two of which are against immovable walls. The two identical gaps between the sections are provided so that thermal expansion...
July 25, 2013

physics
An aluminum can is filled to the brim with a liquid. The can and the liquid are heated so their temperatures change by the same amount. The can’s initial volume at 8 °C is 4.8 × 10-4 m3. The coefficient of volume expansion for aluminum is 69 × 10-6 (C°...
July 25, 2013

general physics
When you take a bath, how many kilograms of hot water (40.8 °C) must you mix with cold water (11.3 °C) so that the temperature of the bath is 30.9 °C? The total mass of water (hot plus cold) is 190 kg. Ignore any heat flow between the water and its external ...
July 25, 2013

physics
I cant find it please specify
July 17, 2013

physics
A airplane is approaching you at a speed of 360km/h. If you measure the pitch of its approaching engines to be 512 Hz, what must be the actual frequency of the sound of the engines? The speed of sound in air is 345m/s answer is 364Hz please explain steps?
July 17, 2013

Physics
The pressure exerted by a phonograph needle on a record is surprisingly large. If the equivalent of 1.00 g is supported by a needle, the tip of which is a circle 0.200 mm in radius, what pressure is exerted on the record in N/m2?
July 14, 2013

Physics
A straightforward method of finding the density of an object is to measure its mass and then measure its volume by submerging it in a graduated cylinder. What is the density of a 240-g rock that displaces 89.0 cm3 of water? (Note that the accuracy and practical applications of...
July 14, 2013

Physics
What is the final velocity of a hoop that rolls without slipping down a 5.00-m-high hill, starting from rest?
July 14, 2013

Physics
. (a) Calculate the angular momentum of an ice skater spinning at 6.00 rev/s given his moment of inertia is 0.400 kg ⋅ m2. (b) He reduces his rate of spin (his angular velocity) by extending his arms and increasing his moment of inertia. Find the value of his moment of ...
July 14, 2013

Physics
What is the moment of inertia of an object that rolls without slipping down a 2.00-m-high incline starting from rest, and has a final velocity of 6.00 m/s? Express the moment of inertia as a multiple of MR2, where M is the mass of the object and R is its radius.
July 14, 2013

Physics
Suppose you exert a force of 180 N tangential to a 0.280-m-radius 75.0-kg grindstone (a solid disk). (a)What torque is exerted? (b) What is the angular acceleration assuming negligible opposing friction? (c) What is the angular acceleration if there is an opposing frictional ...
July 14, 2013

physics
calculate the energy consumed by a computer(150 W) that is used for 2.0 hours and a laser(250 W) that is used for 10 min? Answer is 1.2 Mj
July 10, 2013

physics
A 54.5-kg passenger in the back seat of a van is wearing a seat belt when the van runs into a stone wall. The van is originally moving at 12.6 m/s. The front end of the van collapses 0.624 m as the van comes to rest. (a) Determine the passenger’s kinetic energy before the...
July 10, 2013

Maths
20sin55 is equal to 16.4 m
July 10, 2013

physics
A 0.662-kg basketball is dropped out of a window that is 6.32 m above the ground. The ball is caught by a person whose hands are 1.82 m above the ground. (a) How much work is done on the ball by its weight? What is the gravitational potential energy of the basketball, relative...
July 8, 2013

physics
A semi-trailer is coasting downhill along a mountain highway when its brakes fail. The driver pulls onto a runaway truck ramp that is inclined at an angle of 13.0° above the horizontal. The semi-trailer coasts to a stop after traveling 190 m along the ramp. What was the ...
July 8, 2013

physics
A pendulum bob swinging at a velocity of 10 m/sec would rise how high from its lowest point of its swing
July 6, 2013

physical science
A student, starting from rest, slides down a water slide. On the way down, a kinetic frictional force (a nonconservative force) acts on her. The student has a mass of 82 kg, and the height of the water slide is 11.3 m. If the kinetic frictional force does -6.2 × 103 J ...
July 3, 2013

physics
At a carnival, you can try to ring a bell by striking a target with a 11.6-kg hammer. In response, a 0.413-kg metal piece is sent upward toward the bell, which is 4.22 m above. Suppose that 26.2 percent of the hammer's kinetic energy is used to do the work of sending the ...
July 3, 2013

Phys
Starting from rest, a 1.6x10-4 kg flea springs straight upward. While the flea is pushing off from the ground, the ground exerts an average upward force of 0.38 N on it. This force does 2.6x10-4 J of work on the flea. (a) What is the flea's speed when it leaves the ground...
July 3, 2013

physics
A dynamite blast at a quarry launches a rock straight upward, and 2.2 s later it is rising at a rate of 17 m/s. Assuming air resistance has no effect on the rock, calculate its speed (a) at launch and (b)4.4 s after launch.
July 2, 2013

Gen physics
A 13,900 kg truck is moving at 23.5 m/s on a mountain road when the brakes are applied. The brakes FAIL!! Fortunately, the driver sees a deceleration (ouch!) ramp a short distance ahead. This is an incline used by out of control trucks to dissipate their KE by converting it to...
July 1, 2013

physics
A 34.1 kg child rides a Ferris wheel whose diameter is 18.3 m. When the ride is turning at a constant rate, the child’s speed has a constant value of 4.23 m/s. Find the normal force the seat exerts on the child at: a) The top of the ride b) The bottom of the ride
July 1, 2013

Physics
A 13,900 kg truck is moving at 23.5 m/s on a mountain road when the brakes are applied. The brakes FAIL!! Fortunately, the driver sees a deceleration (ouch!) ramp a short distance ahead. This is an incline used by out of control trucks to dissipate their KE by converting it to...
July 1, 2013

general physics
COMPLETELY STUCK? The period of rotation of the Moon is about 27 days, 8 hrs. The mass of the Moon is 7.35 x 1022 kg, and the radius of the Moon is 1.74 x 106 m. I wish to place a synchronous (period of orbit = period of the Moon’s rotation) satellite in orbit about the ...
July 1, 2013

general physics
His spacecraft, Vostok I, was a sphere about 2.3 m in diameter, and it reached a maximum altitude above Earth’s surface of 327 km. What was the spacecraft’s speed at this point in its orbit?
July 1, 2013

physics
starting from rest, find a 54.6kg child’s speed at the bottom of a 15.5m tall slide if it is assumed to be frictionless
July 1, 2013

Physics
1. a) Dy = Viy(t) + (1/2)(g)t^2 15.5 m = 0(t) + (1/2)(9.8 m/s^2)(t^2) t = sqrt[(15.5 m)/(4.9 m/s^2)] t = 1.8 sec answer b) Let V = speed of the ball just before it strikes the water. Vix = Vfx = 11.4 m/s Vfy = Viy + gt Vfy = 0 + (9.8 m/s^2)(1.8 s) Vfy = 17.64 m/s V = sqrt[Vfx^...
June 18, 2013

Physics
A golf ball rolls off a horizontal cliff with an initial speed of 12.2 m/s. The ball falls a vertical distance of 17.3 m into a lake below. (a) How much time does the ball spend in the air? (b) What is the speed v of the ball just before it strikes the water?
June 18, 2013

Physics
A meteoroid is speeding through the atmosphere, traveling east at 23.1 km/s while descending at 18.3 km/s. What is its speed, in km/s?
June 18, 2013

Physics
In a football game a kicker attempts a field goal. The ball remains in contact with the kicker's foot for 0.0475 s, during which time it experiences an acceleration of 417 m/s2. The ball is launched at an angle of 59.7° above the ground. Determine the (a) horizontal ...
June 18, 2013

Physics
A tennis ball is struck and departs from the racket horizontally with a speed of 27.3 m/s. The ball hits the court at a horizontal distance of 18.7 from the racket. How far above the court is the tennis ball when it leaves the racket?
June 18, 2013

math
vlad purchased some furniture for his apartment. The total cost was $2942.37. He paid $850 down and financed the rest for 18 months. At the end of the finance period. Vlad owed 2147.48. What annual interest rate compounded monthly eas he being charged? round your answers to ...
June 10, 2013

chemistry
How many liters of 20 Volume H2O2 will contain one mole of hydrogen peroxide?
June 2, 2013

math
Please help! :-)
May 28, 2013

math
108 ,36,12,4 ___ ,____find next two numbers 12,24 ,48,96 ____, ___ find the next two numbers 1 ,1,2,3 ____, ____ find the next two numbers
May 28, 2013

math
1.) Calculate the area of a circle with radius 8.5 inches. . 2.) Calculate the area of a circle with the diameter 15 feet. . 3.) Calculate the area of a circle with radius 9 feet
May 19, 2013

science
A science teacher tells her class that their final project requires the students to measure a specific variable and determine the velocity of a car with no more than 2.5% error. Jennifer and Johnny work hard and decide the velocity of the car is 34.87 m/s. The teacher informs ...
May 19, 2013

math
Oh ok Thank you
May 15, 2013

math
Would that be in inches
May 15, 2013

math
Draw and label a rectangle that has an area of 18 square units? . How much is that in width and length.
May 15, 2013

calculus
please anyone help me out Consider the following. Function Point f(x) = 5x^2 − 4, (3, 41) Find an equation of the tangent line to the function at the given point. y = Find the function values and the tangent line values at f(x + Δx) and y(x + Δx) for Δx...
May 4, 2013

math calculus
The concentration C (in milligrams per milliliter) of a drug in a patient's bloodstream t hours after injection into muscle tissue is modeled by C = 3t/26 + t^3 Use differentials to approximate the change in the concentration when t changes from t = 1 to t = 1.5. (Round ...
May 4, 2013

math calculus
hey bobpursley i tried this one on my own but i dont get the right answer i mean if u can give me the solution i will look at it thanks
May 4, 2013

Algebra
Hearst Castle is 180 miles from Ventura by road. Two coaches leave Ventura at the same time, both heading for Hearst Castle, but one averages 5 mph faster than the other. If the faster coach reaches Hearst Castle half an hour earlier than the slower coach, what is the average ...
April 28, 2013

math
What am I? I have four digits is 1. The product of my digits is 0
April 22, 2013

geomtry
find the arc length of the minor arc withe degree of 120 and a radius of 8
April 18, 2013

Algebra.. PLEASE help me!!
e=mc2
April 11, 2013

LA
i think its B or C
April 11, 2013

LA
How did the Civil War affect the Northern and Southern economies? A;The North experienced more severe inflation than the South. B;Overall the South fared much worse economically than the North. C;The South experienced a boom in manufacturing. D;The North's economy was ...
April 11, 2013

LA
How did the Civil War affect the Northern and Southern economies? A;bounties B;greenbacks C;draft D;habeas corpus
April 11, 2013

Algebra
A theater company's annual profit is modeled by the equation P= 0.2x^2-6.8x, where x is the number of plays performed in a year. How many plays must the company present in order to make a profit?
March 28, 2013

Algebra
Mr. Jones estimate his profit starting in 2006 will be given by the formula P=7t^2-14t+10 where t is number of years and P is the profit. If this formula is correct, when will Mr. Jones have a profit of more than $1000.00?
March 28, 2013

statistics
two spot available and there is 6 men and 4 women what is the probability that a women will be picked?
March 22, 2013

US History
can somebody answer it
March 1, 2013

physics
Two point charges totaling 9.00 µC exert a repulsive force of 0.300 N on one another when separated by 0.596 m. (A) What is the charge on each? (B) What is the charge on each if the force is attractive? smallest charg
February 28, 2013

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