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April 20, 2014

Homework Help: Science: Physics

Recent Homework Questions About Physics

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Physics Please help!
Using the parallel axis theorem, we know that I = I_cm + mr^2, where r is the amount of displacement from the symmetry axis. And we know that for a solid cylinder, I_cm = 1/2(mr^2); Further, for a solid sphere I_cm = 2/5(mr^2) (a) ==> I = 1/2(mr^2) + mr^2 = 3/2(mr^2) = 3/2(...
Tuesday, March 25, 2014 at 9:27pm

Physics
h=(V^2-Vo^2)/2g = (0-(8^2))/-19.6=3.27 m
Tuesday, March 25, 2014 at 8:56pm

Physics
The bulk modulus of a liquid is 4.0 10^10 N/m2. Suppose a volume of 0.6 m3 of the liquid is taken from the surface where the pressure is approximately that of the atmosphere (1.00 10^5 N/m2) and is lowered into a pool of liquid to a depth where the pressure is 2.00 10^7 N/m2. ...
Tuesday, March 25, 2014 at 8:38pm

physics
What is the pressure that is exerted by a box tjat has a dimension of 12cm long and 14cm wide and has a force of gravity on the box of 40N?
Tuesday, March 25, 2014 at 8:36pm

physics
vf^2=vi^2 + 2gd g=-9.8m/s^2, d=.180 m, vi given. mass is not needed.
Tuesday, March 25, 2014 at 8:35pm

Physics
A 150g piece of copper is heated to 100oC. It is then held in the open air for 2 minutes and 31 seconds, and then dropped into a 100g copper calorimeter containing 200g of water at 17oC. If the rate of loss of heat of the copper piece while held in the air is 12.6J/sec, ...
Tuesday, March 25, 2014 at 8:34pm

Physics
Ok, but then how do you find Tf?
Tuesday, March 25, 2014 at 8:34pm

physics
A 100-g toy car is propelled by a compressed spring that starts it moving. The car follows the curved track Show that the final speed of the toy car is 0.687 m/s if its initial speed is 2.00 m/s and it coasts up the frictionless slope, gaining 0.180 m in altitude
Tuesday, March 25, 2014 at 8:33pm

Physics
The sum of the heats gained is zero. heatgainedwater+heatgainedAl=0 86.8*cwater*( Tf-90 )+60*calum*(Tf-25)=0
Tuesday, March 25, 2014 at 8:31pm

Physics
An aluminum calorimeter has a mass of 60g and an initial temperature of 25oC. What is the final temperature attained when 86.8g of water at 90oC is poured into it?
Tuesday, March 25, 2014 at 8:24pm

physics
V = d/t = (t^3-3t^2+2)/4=(4^3-3*4^2+2)/4 = 4.5 m/s.
Tuesday, March 25, 2014 at 8:08pm

Physics
Been there, done that scroll down .
Tuesday, March 25, 2014 at 7:59pm

Physics
well if you started out with everything neutral and one got negative then the other got positive (the rod stole electrons from the wool, becoming negative. That left the wool with an excess of protons, becoming positive)
Tuesday, March 25, 2014 at 7:59pm

Physics
When a rubber rod is rubber with wool, the rod becomes negatively charged. What can you conclude about the magnitude of the wool's charge after the rubber process? Why? Please Help!!
Tuesday, March 25, 2014 at 7:57pm

physics
tan Theta = 50/100 Theta = 26.6 degrees
Tuesday, March 25, 2014 at 7:56pm

Physics
When a rubber rod is rubber with wool, the rod becomes negatively charged. What can you conclude about the magnitude of the wool's charge after the rubber process? Why? Please Help!!
Tuesday, March 25, 2014 at 7:56pm

physics
In a water park, people walk up a ramp before diving into the water below. If they cover a horizontal distance of 100 meters before diving down 50 meters, what is the angle made by the ramp with the ground?
Tuesday, March 25, 2014 at 7:50pm

physics
To be ever so much easier to find X for the algebraically challenged. X= d*SQRT(K*q1*q3)/SQRT(K*q2*q3)+ SQRT(K*q1*q3)
Tuesday, March 25, 2014 at 6:22pm

physics 1
Hey, wait a minute. If there were no gravity it would have taken less time to stop. The total force up including gravity = change of momentum so there is no change to the force in part b due to gravity.
Tuesday, March 25, 2014 at 6:18pm

physics 1
force = rate of change of momentum = 88.1*3.53 / .00356 = 87,358 N = 88.1*3.53/.199 = 1,563 N with gravity add 88.1*9.81 = 864 N
Tuesday, March 25, 2014 at 6:13pm

physics
v=v₀+at = 10.5+(4.4•4.2) = 28.98 m/s
Tuesday, March 25, 2014 at 6:04pm

physics
trtytyyyvvvvvvvvv
Tuesday, March 25, 2014 at 6:02pm

physics
v₁ =910 m/s m₂=1000 kg v₂=10000 m/s u= 1000 m/s m₁=? (m₁+m₂)u = m₁v₁ +m₂v₂ m₁=m₂(v₂-u)/(u-v₁​;)= =1000(10000-1000)/(1000-910) = 100000 kg
Tuesday, March 25, 2014 at 5:56pm

physics 1
When jumping straight down, you can be seriously injured if you land stiff-legged. One way to avoid injury is to bend your knees upon landing to reduce the force of the impact. A 88.1-kg man just before contact with the ground has a speed of 3.53 m/s. (a) In a stiff-legged ...
Tuesday, March 25, 2014 at 5:45pm

physics
initial momentum = 1000 m final momentum = 910(m-1,000) + 10^7 90 m = .091*10^7 + 10^7 = 1.091*10^7 m = 121,222 kg
Tuesday, March 25, 2014 at 5:44pm

physics
The mass of the electron is 1.6 x 10^-19 kg The mass of the proton is 1.66 x 10-27 kg
Tuesday, March 25, 2014 at 5:42pm

Physics
gain in energy = m g h = 1.2 * 9.81 * 34.2 = 403 Joules 403 = (1/2) m v^2 + (1/2)I omega^2 I = m r^2 = 1.2 (.09) = .108 omega = v/r = v/0.3 so 403 = (1/2)(1.2)(v^2) +(1/2)(.108)(v^2)/.09 403 = v^2 ( .6 + .583) v = 18.5 m/s I agree with you
Tuesday, March 25, 2014 at 5:29pm

physics
a spaceship is moving at 1000 m/s release a satellite of mass 1000 kg at a speed of 10 000 m/s. what is the mass of the spaceship if it slows down to a velocity of 910 m/s?
Tuesday, March 25, 2014 at 4:43pm

Physics
Assume that all of the mass of a bicycle wheel is concentrated at its rim. Such a wheel of mass 1.2 kg and radius 30 cm starts from rest at the top of a hill 100m long and inclined at 20 degrees to the horizontal. What will be the speed of the wheel at the bottom of the hill ...
Tuesday, March 25, 2014 at 4:29pm

physics
a spaceship is moving at 1000 m/s release a satellite of mass 1000 kg at a speed of 10 000 m/s. what is the mass of the spaceship if it slows down to a velocity of 910 m/s?
Tuesday, March 25, 2014 at 4:28pm

Physics
Help me understand this please You have a 2.00 kg block of lead. Lead melts at 327.5°C. CPb = 130.0 , and Hf for lead is 2.04 × 10^4 J/kg. Say you start at room temperature (25.0°C). How much heat must you transfer to melt all the lead?
Tuesday, March 25, 2014 at 4:17pm

PHysics XXX
s = 1/2 at^2, so a = 2s/t^2 v = at = (2s/t^2)t = 2s/t = 73.3 m/s
Tuesday, March 25, 2014 at 1:06pm

physics
A car entering the freeway accelerates from 10.2 m/s with a constant acceleration of 4.4 m/s2. What is the car’s final velocity when it merges onto the highway and reaches its cruising speed 4.2 seconds later? A 28.7 m/s B 11.2 m/s C 18.5 m/s D 8.28 m/s
Tuesday, March 25, 2014 at 1:00pm

PHysics XXX
An airplane travels 330 m down the runway before taking off. Assuming that it has constant acceleration, if it starts from rest and becomes airborne in 9.00 s, how fast (in m/s) is it moving at takeoff? A 73.3 m/s B 36.7 m/s C 1490 m/s D 660 m/s
Tuesday, March 25, 2014 at 12:58pm

Physics
the cutoff frequency is r/(2pi L) = 15/(2pi*5.6 * 10^-3) = 426 Hz
Tuesday, March 25, 2014 at 12:01pm

Physics
5
Tuesday, March 25, 2014 at 11:29am

Physics
Assuming friction is not velocity dependent, the the friction is 5N. if one pulls with 25N net force=m*a 25-5=5 a solve for a
Tuesday, March 25, 2014 at 11:11am

Physics
An object with a mass of 5 kg moves at a constant velocity when it is pulled by a horizontal force of 5 N on a level surface. What is the acceleration of the object if the object is pulled with a force of 25 N?
Tuesday, March 25, 2014 at 9:49am

Physics
F = MA F = qv*B ma = qvb a = qbv/m m = mass of electron q = charge of electron
Tuesday, March 25, 2014 at 9:45am

Physics
In Stranger in a Strange Land, Robert Heinlein claims that travelers to Mars spent 258 days on the journey out, the same for return, \plus 455 days waiting at Mars while the planets crawled back into positions for the return orbit." Show that travelers would have to wait ...
Tuesday, March 25, 2014 at 9:05am

physics
this is a physics qustion im stuck on: ingrid holds the womans record time for a marathon race of 2h 21min 6s for 42.195km. The mens record is held by Blake grison of 2h 6 min 50s. If they had been in the same race how much would blake win by.. find this in time as well as ...
Tuesday, March 25, 2014 at 7:56am

Physics
A series RCL circuit contains only a capacitor (C=6.60 F), an inductor (L=7.20 mH), and a generator (peak voltage=32.0 V, frequency=1.50x10^3 Hz). When t  0 s, the instantaneous value of the voltage is zero, and it rises to a maximum one-quarter of a period later. (a) ...
Tuesday, March 25, 2014 at 3:27am

physics
Determine the distance to which the 90 kg painter can climb without causing the 4 m ladder to slip at its lower end A as shown in Figure 1. The top of the 15 kg ladder has a smaller roller, and at the ground the coefficient of static friction is 0.25. The mass center of the ...
Tuesday, March 25, 2014 at 2:48am

physics
1 - Determine the distance to which the 90 kg painter can climb without causing the 4 m ladder to slip at its lower end A as shown in Figure 1. The top of the 15 kg ladder has a smaller roller, and at the ground the coefficient of static friction is 0.25. The mass center of ...
Tuesday, March 25, 2014 at 2:32am

physics
thanks Henry!
Tuesday, March 25, 2014 at 1:25am

physics
I don't know
Tuesday, March 25, 2014 at 12:58am

Physics
A series circuit contains only a resistor and an inductor. The voltage V of the generator is fixed. If R = 15 and L = 5.6 mH, find the frequency at which the current is one-half its value at zero frequency. ?? Hz Thanks!
Monday, March 24, 2014 at 11:46pm

physics
picture webassign . net/pse/p28-23.gif The ∑ symbol is just epsilon for the voltage in the picture
Monday, March 24, 2014 at 11:45pm

physics
hi
Monday, March 24, 2014 at 11:44pm

physics
A compact disk player has just been turned off. A disk decelerates uniformly from an initial angular velocity of 7.90 rev/s. The disk rotates through 5.50 revolutions before coming to rest. What is the tangential acceleration of a point on the disk 5.05 cm from the axis?
Monday, March 24, 2014 at 10:51pm

Physics #2
4.7m/s
Monday, March 24, 2014 at 10:46pm

physics
a. 1.5km * 1000m/km * 1*10^6um/m = 1.5*10^9 Microns. b. 1.5um * 1m/10^6um * 100cm/m = 1.5*10^-4 cm c. 1.5yds * 3Ft/yd * 1m/3.3Ft * 10^6um/m = 1.364*10^6 Microns.
Monday, March 24, 2014 at 10:40pm

physics
h=(V^2-Vo^2)/2g = (0-(-8^2)/-19.6 = 3.27 m.
Monday, March 24, 2014 at 10:11pm

Physics
D- Transverse
Monday, March 24, 2014 at 9:59pm

physics
T = 3 25/60 + (7 35/60-3 25/60) T = 3.417 + (7.583-3.417) = 7.583 Min. = 455 s. t = (7.583-3.417)min * 60s/min = 250 s. d = V*t = 1.65m/s * 250s = 412.4 m. V = d/T = 412.4m/455s = 0.906 m/s.
Monday, March 24, 2014 at 9:55pm

Physics
A wagon is coasting at a speed vA along a straight and level road. When twenty-five percent of the wagon's mass is thrown off the wagon, parallel to the ground and in the forward direction, the wagon is brought to a halt. If the direction in which this mass is thrown is ...
Monday, March 24, 2014 at 9:46pm

Physics
f
Monday, March 24, 2014 at 9:28pm

physics
See Previous Questions: Fri,3-21-14, 8:55PM.
Monday, March 24, 2014 at 8:53pm

Physics
A box of mass 54.0 kg is sitting on a ramp which makes an angle of 37.0 degrees with respect to the horizontal. The coefficient of friction between the box and the ramp is 0.21. This box is connected by a massless string over a pulley at the top of the ramp to a second box ...
Monday, March 24, 2014 at 8:51pm

Physics
A box of mass 50.0 kg is connected to a second box with a mass of 54.0 kg. Both are sitting on a horizontal surface and the coefficient of kinetic friction between the surface and each box is 0.51. If the second box is pulled away from the first box with a force of 605.8 N, ...
Monday, March 24, 2014 at 8:51pm

Physics
A wave can be propagated on a rope by holding one end of the rope and moving your hand up and down. The resulting wave is: A)neither transverse nor longitudinal. B)both transverse and longitudinal C)longitudinal D)transverse
Monday, March 24, 2014 at 8:17pm

Physics
Two boxes of mass 7.40 and 7.00 kg are in contact and are accelerated across a horizontal surface by an force of 51.49 N applied parallel to the surface and pushing on the lighter box. The magnitude of the frictional force between the surface and the lighter mass is 9.26 N and...
Monday, March 24, 2014 at 8:09pm

Physics
Two blocks of weights 77.0 and 114.0 N are connected by as massless string and slide down an inclined plane making an angle of 45.0 deg. to the horizontal. The cofficient of kinetic friction between the lighter block and the plane is 0.15 and that between the heavier block and...
Monday, March 24, 2014 at 8:08pm

Physics
A railroad car with a mass of 12000 kg collides and couples with a second car of mass 18000 kg that is initially at rest. The first car is moving with a speed of 9 m/s before collision. If external forces can be ignored, what is the final speed of the two railroad cars after ...
Monday, March 24, 2014 at 8:06pm

Physics
A 5-kg ball is at rest when it is struck head-on by a 2-kg ball moving along a track at 10 m/s. If the 2-kg ball is at rest after the collision, what is the speed of the 5-kg ball after the collision?
Monday, March 24, 2014 at 8:05pm

Physics
40 miles per hour
Monday, March 24, 2014 at 7:39pm

physics please help!!
A diver stands on the end of a diving board as shown in the figure on the right. The mass of the diver is 58 kg and the mass of the uniform diving board is 35 kg. Calculate the magnitudes and directions of the forces exerted on the board at the points A and B. (A & B are 1 ...
Monday, March 24, 2014 at 7:11pm

Physics( Explain and choose right answer)
Like here: http://www.jiskha.com/display.cgi?id=126​0400554
Monday, March 24, 2014 at 7:08pm

Physics
Please help!
Monday, March 24, 2014 at 7:08pm

Physics( Explain and choose right answer)
change in momentum = Force * time m v = force*time You would have to guess force, mass and final speed to approximate time. If you look at some of the problems down below you may find reasonable assumptions to make
Monday, March 24, 2014 at 7:08pm

Physics
please help asap
Monday, March 24, 2014 at 7:07pm

Physics( Explain and choose right answer)
The tension is smallest at the top, if the speed is in fact enough to make the top without the tension going to zero. At top: Tension + m g = m v^2/R tension = m (v^2/R - g) if the centripetal acceleration is not greater than g, the rope goes slack.
Monday, March 24, 2014 at 7:05pm

Physics( Explain and choose right answer)
actually speed rather than velocity because directions are opposite.
Monday, March 24, 2014 at 7:02pm

Physics( Explain and choose right answer)
initial momentum = 0 so final momentum = 0 0 = 3*Vcat + 1.5*Vcardboard so Vcardboard = 3 Vcat/1.5 = 2 Vcat
Monday, March 24, 2014 at 7:01pm

physics
A person has a choice while trying to move a crate across a horizontal pad of concrete: push it at a downward angle of 30 degrees, or pull it at an upward angle of 30 degrees. If the crate has a mass of 50.0 kg and the coefficient of friction between it and the concrete is 0....
Monday, March 24, 2014 at 6:56pm

Physics
A 115.0 kg box is pushed by a horizontal force F at constant speed up a frictionless ramp which makes an angle of 46.0 deg with the horizontal.what is the magnitude of the normal force between the ramp and the box? The applied force= 1167.04N
Monday, March 24, 2014 at 6:52pm

Physics( Explain and choose right answer)
A ball on the end of a rope is moving in a vertical circle near the surface of the earth. Point A F T is at the top of the circle; C is at the bottom. Points B and D are exactly halfway between A and C. Which one of the following statements concerning the tension in the rope ...
Monday, March 24, 2014 at 6:40pm

Physics( Explain and choose right answer)
How long is a golf club in contact with a golf ball for? A. 0.5 seconds B. 0.1 seconds C. 0.01 seconds D. 0.001 seconds E. 0.0001 seconds F. Too short to measure
Monday, March 24, 2014 at 6:35pm

Physics
327.5x25.0=302.5 T= 302.5C q=2.00kg(130.0 kqc) (302.5c) q=H&M Q=78,650J Q=2.04x10^4 j/kg (2.00g)=40,800J Q=119,450J „³ 119,000J
Monday, March 24, 2014 at 6:34pm

Physics( Explain and choose right answer)
A 3 kg cat sitting on a 1.5 kg piece of cardboard on a frozen lake wants to jump to shore without touching the ice. If there is no friction between the cardboard and the ice, when the cat jumps. the cardboard will move in the opposite direction with a velocity: A. half as ...
Monday, March 24, 2014 at 6:31pm

Physics
The drawing shows an equilateral triangle, each side of which has a length of 2.20 cm. Point charges are fixed to each corner, as shown. The 4.00 µC charge experiences a net force due to the charges qA and qB. This net force points vertically downward and has a magnitude...
Monday, March 24, 2014 at 6:29pm

Physics
A 2.00-kg object is hanging on a 1.1m string. The object is pulled 20cm away from the equilibrium position and held there. a) What is the pulling force in the string when the object is kept still ? b) Now the object is released, what is the speed of the object when it goes ...
Monday, March 24, 2014 at 6:17pm

Physics
A 5.1- kg concrete block rests on a level table. A 3.4- kg mass is attached to the block by a string passing over a light, frictionless pulley. If the acceleration of the block is measured to be 1.3 m/s2, what is the coefficient of friction between the block and the table? ...
Monday, March 24, 2014 at 5:06pm

Physics
A ladder, 5.0 m long, leans against a frictionless wall at a point 4.0 m above the ground. A painter is climbing up the ladder. The mass of the ladder is 12.0 kg and the mass of the painter is 60.0 kg. The ladder begins to slip at its base when the painter is 70 % of the way ...
Monday, March 24, 2014 at 4:41pm

Physics
A diver stands on the end of a diving board as shown in the figure on the right. The mass of the diver is 58 kg and the mass of the uniform diving board is 35 kg. Calculate the magnitudes and directions of the forces exerted on the board at the points A and B. A and B are 1m ...
Monday, March 24, 2014 at 4:39pm

Physics
C + O2 ---> Co2 gas and heat (combustion) Heat of vaporization + water ---> steam under pressure Expanding steam ---> kinetic energy of H2O molecules passing blades and moving them blades turn hub, torque * angular speed is rotational mechanical energy Moving coils in...
Monday, March 24, 2014 at 3:49pm

Physics
Water is boiled by burning coal. The resulting steam blows agains huge turbine blades. The turning blades spin in a magnetic field, producing electricity. Describe in order the energy conversions.
Monday, March 24, 2014 at 3:42pm

Physics
A small block on a frictionless surface has a mass of 70 g. It is attached to a massless string passing through a hole in a horizontal surface (see diagram). The block is originally rotating in a circle of radius 45 cm with angular speed 0.80 rad/s. The string is then pulled ...
Monday, March 24, 2014 at 2:56pm

physics
From a to b Wg= Fx cos 90 = 0 Wn= Fx cos 90 = 0 Wnet=Efk - Eik. Which is = to 1/2mVf^2 -1/2 mVi^2. Fxcos(0)= Efk. Cos of 0 =1. Vi =0 so use Efk Fx=1/2mVf^2 2Fx/m = Vf^2 Vf^2= square root of2Fx/m Vf= 9.77m/s X = distance, m= mass, F= force, V= velocity Efk = final kinetic ...
Monday, March 24, 2014 at 2:48pm

physics
7. ( 11E ) a) Find the momentum of an automobile of mass 2630 kg traveling 21.0 ms .b) Find the velocity ( in km/h ) of a light auto of mass 1170 kg so that it has the same momentum as the auto in part ( a ).
Monday, March 24, 2014 at 2:08pm

physics
a wheelof diameter 0.70 meterolls without slipping. a point at the top of the wheel moves with a tangential speed of 2.0 meter/second. a) at what speed is the axis of the wheel moving? b) What is the angular speed of the wheel?
Monday, March 24, 2014 at 1:10pm

physics
I do not understand the direction of the 35N force.
Monday, March 24, 2014 at 12:43pm

Physics
Find the total change in the internal energy of a gas that is subjected to the following two-step process. In the first step the gas is made to go through isochoric heating until it gains 5363 J and its pressure is 2.92 105 Pa. In the second step it is subjected to isobaric ...
Monday, March 24, 2014 at 12:42pm

physics
A bookshelf is at rest in a room. A force of 35.0 newtons is applied to a bookshelf. If the floor imparts a frictional force of 2.90 newtons, what is the net force acting on the bookshelf?
Monday, March 24, 2014 at 12:36pm

physics
Consider a toy car that you pullback to make it go forward. Is it a force multiplier or a distance multiplier? Defend your answer with the observations you could make
Monday, March 24, 2014 at 12:06pm

physics
explain the input energy and out put energies of two kitchen machines
Monday, March 24, 2014 at 12:05pm

Physics
explain the input energy and out put energies of two kitchen machines
Monday, March 24, 2014 at 12:05pm

physics
if you throw a 0.2 kg ball straight up at 8 m/s how high will it go
Monday, March 24, 2014 at 12:05pm

Physics
assume the weight of the hanging down mass to be M2, with the other mass is horizonal movement, and mass M1 net force=m2*g=totalmass*a m2*g=(M1+M3)a now tension between them. the tension is pulling mass1 tension=m1*a or, tension is holding back M2 and m2g-tension=M2a either ...
Monday, March 24, 2014 at 12:00pm

Physics
Hmmm. I need more details, I am uncertain what you are visualizing here.
Monday, March 24, 2014 at 11:56am

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