# Posts by Physics

Total # Posts: 436

**Physics**

A ball is thrown horizontally from the roof of a building 9.0 m tall and lands 8.5 m from the base. What was the ball's intial speed? I have no idea how to do this problemm or what formulas to use because of the fact that I do not know the time interval it took to fall. ...

**Physics**

huh ok thanks i thought sense the end vector was south perfectly south... ok makes sense direction of displacement vector I guess is what it means by direction... Thanks!

**Physics**

A delivery truck travels 18 blocks north, 10 blocks east, and 16 blocks south. what is its final displacement from the origin? assume the blocks are equal length. My only question is I got about 10 blocks for the displacement got a 2 opposite and 10 adjacent and had to solve ...

**Physics**

I'm trying to rearange this 0 = Xo + 2^-1 a t^2 for t I've been told that it is (a^-1 2x)^(2^-1) but I do not see how please show me step by step how you get that 0 - Xo = Xo - Xo + 2^-1 a t^2 (-Xo = 2^-1 a t^2) a^-1 2 (a^-1 (2-Xo) = t^2)^(2^-1) (a^-1 (2 - Xo))^(2^-1) ...

**Physics**

when trying to find uncertanty percent error and your given the number - 15 s^-2 m with a implied uncertanty of +/- 1 s^-2 m and you try to find the percent uncertanty and you do this (- 15 s^2 m)^-1 1 s^-2 m (100 %) is the percent negative or positve also when trying to find ...

**physics**

the speed of a car can be measured in s^-1 m right... it could be said that a speed of a car the velocity was 15 s^-1 m which is perfectly acceptable... by definition 15 s^-1 m can also be written as 15 Hz m just by definition... what on earth does that mean??? is velocity not...

**physics**

Thank You

**physics**

can you show me how to do this mathematically A car traveling 90 km/h is 100 m behind a truck traveling 75 km/h. How long will it take the car to reach the truck?

**Physics**

def of average velocity = t^-1 (x - x0) (average velocity = t^-1(x-x0))t=(avearge velocity)t + x0= x - x0 + x0 = x = (average velocity)t + x0 x = (average velocity)t + x0 def of average velocity were costant acceleration is assumed = 2^-1(v0 + v) plug into x = (average ...

**Physics**

def of average velocity = t^-1 (x - x0) (average velocity = t^-1(x-x0))t=(avearge velocity)t + x0= x - x0 + x0 = x = (average velocity)t + x0 x = (average velocity)t + x0 def of average velocity were costant acceleration is assumed = 2^-1(v0 + v) plug into x = (average ...

**physics**

also what is the max potential energy??? I don't know how to solve for max velocity unless I can solve for total energy

**physics**

also what does solving for W do??

**physics**

I'm given a spring that has a mass of 100 g and a constant of 22 N/m with an A of 5 cm I belive the A is amplitude and I'm asked for the Total Energy which i don't know how to do the max velocity also have no idea how to do and the max force which i don't know ...

**Physics**

I'm given two cars A and B Car A is 1100 kg and traveling at 11 m/s Car B is 1400 kg and traveling at 15 m/s and I'm asked to fidn the velocity of both is just the net velocity 4 m/s ??? I'm also to find the impulse and how would I do that??? impulse is chang in ...

**Sarah**

they got it in cm so 17.6 cm

**Sarah**

A light spring having a force constat of 125 N/m is used to pull a 9.50kg sled on a horizontal frixtionless ice rink. If the sled has an acceleration of 2.00 m/s^2, by how much does the spring stretch if it pulls on the sled (a) horizontally, (b) at 30.0 degrees above the ...

**mary**

The question is: a horizontal force of magnitude 22.0 N is applied to a 2.86 kg book as the book slides a distance d = 0.73 m up a frictionless ramp at angle θ = 30°. The book begins with zero kinetic energy. What is its speed at the end of the displacement? I did W=...

**Physics**

Hello can some one show and exlpain to me the derivation of this formula? V = (Ft(mL^-1)^-1)^(2^-1) or simply V = sqrt (F/(m/L)) were V = the veloctiy of a piece of string Ft = the force of tension m = mass L = length Thank you!

**jane**

1. a centripetal-acceleration addict rides in uniform circular motion with period T=2s and radius r=3m. at t1 his acceleration vector= 6(m/s^2)i + -4(m/s^2)j. At that instant, what are the values of vector b (dot) vector a and vector r (dot) vector a All I could figure out was...

**charley**

tinyurl--qwxgbv (The qwxgbv is after the slash) The proton moves through a magnetic field of magnitude 3x10^-5 T with a velocity of 4x10^5 m/s. Find the radius of the circular path the proton follows and indicate its direction of rotation.

**9th grade classes**

CABBA

**Physics**

I don't know how to answer this questin i guess I don't understand the definition A streteched sgtring fized at both ends is 2.0 m long. What are three wavelengths that will poduce standing waves on the string? Name at least one wavelenght that would not produce a ...

**Physics**

How do i Do this A wave of amplitude 0.30 m interfers witha second wave of amplitude 0.20 m. What is the largest resultant displacement that may occur?

**Physics**

I lied I didn't get kg^(1/2) m^(1/2) s like I said before I prove my answer I got this which is the last line of my proof (Kg^(1/2) s)/(m^(1/2))

**Physics**

Hello recently I was asked to find the time it takes a satalite that is geocentric (that always stays above the same exact spot of the earth) so... I was given the radius of 61 earth radius or simply 3.89 E 6 m mass of earth what G equals and have to use Newtons law of ...

**Physics**

I'm not exactly sure how to do this problem The Earth has a radius of 6.37E6 meters. Draw a picture and calculate: - The circumference of the Earth - The time for one rotation of the earth in seconds - The velocity of someone standing on the equator - The centripetal ...

**Physics**

I'm not exactly sure how to do this problem The Earth has a radius of 6.37E6 meters. Draw a picture and calculate: - The circumference of the Earth - The time for one rotation of the earth in seconds - The velocity of someone standing on the equator - The centripetal ...

**physics**

So I got this little sheet called Shoot the Chute To be sure you understand the preceeding question and answer, consider this one: A roller coaster is pulled to the top of a "shoot the chute" and allowed to roll down. For a bigger thrill you might wish the car to be ...

**physics**

please check my answer An electron moves north at a velocity of 9.8 * 10^4 m/s and has a magnetic force of 5.6 * 10^-18 N west exerted on it. If the magnetic field points upward, what is the magnitude of the magnetic field? F=BqV F= 5.6 * 10^-18N q= 16 * 10^-19C V= 9.8 * 10^4 ...

**Physics**

could you tell me how to solve for accerating force above friction force? my problem was down below the topic science again

**Physics**

A 15 N wooden block is dragged for 15 meters across a wooden floor in 15 seconds... I'm given that the mew (the greek leter uk) or however u say it is .2 I have to make a free body diagram I sloved and got Fn = 15 N mg = -15 N Ff = -3 N How do I solve for the force applied...

**physics**

please tell me if this is correct, A step-down transformer has 16000 turns on the primary and 95 turns on the secondary. If the rms emf across the secondary coil is 120 V, what is the maximum emf across the primary coil? is the answer 28577.69 V ?

**physics**

please tell me if thsi si correct Two equal charges are separated by 3.7 * 10^-10 m. the force between the charges has a magnitude of 2.37 * 10^-3 N. What is the magnitude of q on the changes? f=1/4pi Er * q^2/r^2 2.37 * 10^-3 = 9*10^9 * q^2 ______________ (3.7 * 10^-10)^2 3....

**physics**

two point charges are 10.0 cm apart and have chargeso of 2.0 uC (micro)and -2 uC, respectively. What is the magnitude of the electric field at the midpoint between the two charges? i think i know how to do it: both E1 and E2 go in the same direction E1=0.72 * 10^7 and E2 = 0....

**physics**

ok, thanks

**physics**

is it .24 amps?

**physics**

The potential differnece across a resistor is 4.4 * 10^2 V. If the resistance of the resistor is 1.8 k ohms, how much current flows throught the resistor? R=1.8 k ohms I=? 4.4*10^2 V V=IR I=V/R = 4.4 * 10^2 ___________ = 2.44*10 1.8 * 10^ 24.4 A is this done correctly?

**physics**

but i checked and it does point in the opposite direction the charges are differnect signs..... i'm confused!

**physics**

two point charges are 10.0 cm apart and have chargeso of 2.0 uC (micro)and -2 uC, respectively. What is the magnitude of the electric field at the midpoint between the two charges? i think the answr is zero.. but i don't understand how to get to it...can you please show me...

**physics**

pleae check How is current affected if the time interval over which the charge passes through a given area decreases while the amount of charge remains the same? a. the current increases b. the current decreases c. the current initially increases and then is gradually restored...

**physics**

What effect will be produced on a capacitor if the separation between the plates is increased? a. it will increase the charge b. it will decrease the charge c. it will increase the capacitance d. it will decrease the capacitance D A 0.25 uF capacitor is connected to a 9.0 V ...

**physics**

please check: A battery converts what type of energy into electrical energy? a. mechanical b. nuclear c. solar d. chemical D When a parallel-plate capacitor is connected to a battery:a____ is stored on one plate, and a ___ is stored on the other a. negative charge, positive ...

**physics**

please check Which of the following is NOT a characteristic of electrical potential energy? a. it is a form of mechanical energy b. it results from a single charge c. it results from the interaction between charges d. it si associated with a charge in an electric field A

**physics**

please check: Two point charges, initially 1 cm apart, are moved to a distance of 3 cm apart. By what factor do the resulting electric and gravitational forces between them change? a. 9 b. 3 c. 1/3 d. 1/9 D Two positive charges, each of magnitude q, are on the y-axis at points...

**physics**

please check: Conductors can be charged by ___, while insulators cannot. a. grounding b. induction c. polarization d. contact D Which of the following is not true for both gravitational and electric forces? a. the inverse square distance law applies b. forces are proportional ...

**physics**

please check this: Which sentence best describes electrical conductors? a. electrical conductors have low mass density b. electrical conductors have high tensile strength c. electrical conductors have electric charges that move freely d. electrical conductors are poor heat ...

**physics**

please check this: When a glass rod is rubbed with silk and becomes positively charged, a. electrons are removed from the rod b. protons are removed from the silk c. protons are added to the silk d. the silk remains neutral A Charge is most easily transferred in a. ...

**physics**

A certain radio wave has a frequency of 2.0*10^6 Hz. What is its wavelength? c=3*10^8 m/s wavelength = 3*10^8 _______ 2*10^6 = 150 m is this done correctly?

**physics**

Monochromatic light from a helium-neon laser (wavelength=632.8 nm) shines at a right angle onto the surface of a diffraction grating that contains 130 960 lines/m. Find the angle at which one would observe the first-order maximum. formula: (a+b)Sin theta = n wavelength (a+b...

**physics**

The critical angle of refraction for calcite is 68.4 degrees when it forms aboundary with water. Use this information to determine the speed of light in calcite. refaraction index 'n' n=cosec 68.4degrees n=1.07 is this done correctly?

**physics**

can you check this : a repelling force occurs between two charged objects when the charges are of a. unlike signs b. like signs c. equal magnitude d. unequal magnitude i chose B

**physics**

An elevator weighing 2.00*10^5 N is supported by a steel cable. What is the tension in the cable when the elevator is accelerated upward at a rate of 3.00 m/s^2? (g=9.81 m/s^2) weight = mg = 2*10^5N = m(9.8) = 2*10^5N mass = m = 2*10^5kg _________ 9.8 = 2.04*10^4kg T-mg=ma T=m...

**physics**

so, how would i write it out? = -0.544 - -3.40 ????????

**physics**

there is a figure that looks kind of like this: E6--------------------- E= -0.378eV E5--------------------- E= -0.544eV E4--------------------- E= -0.850eV E3--------------------- E= -1.51eV E2--------------------- E= -3.40eV the figure shown above shows the enrgy levels for a...

**physics**

ok, thanks...i just want few other people to reply to this post...just to be sure i agree with you but int the one "which of the following statements about electromagenetic..." i'm not sure between B and D thanks again

**physics**

please check these: Which interaction of nature binds atoms and molecules by attracting unlike charges and repulsing like charges? a. strong b. weak c. electromagnetic d. gravitational i got A, but someone said C , so i just want to make sure How is a motor's mechanical ...

**physics**

is this done correctly? A step-down transformer has 16000 turns on the primary and 95 turns on the secondary. If the rms emf across the secondary coil is 120 V, what is the maximum emf across the primary coil? Np=16000 Ns=95 turns Vs=120V Vp=? Ns Vs ___ = ____ Np Vp Ns*Vp=Vs*...

**physics**

A concave mirror forms a real image at 17.0 cm from the mirror surface along the principal axis. If the corresponding object is at ta distance of 36.0 cm, what isi the mirror's focal length? let u be the object distance let v be the image distance v=17 cm u=36 cm 1/f = 1/u...

**physics**

If you stand 3.0 m in front of a flat mirror, how far away from you would yourimage be in the mirror? 6.0 m If light waves are coherent, a. they shift over time b. their intensity is less than that of incoherent light c. they remain in phase d. they have less than three ...

**physics**

please check this one question: Which interaction of nature binds atoms and molecules by attracting unlike charges and repulsing like charges? a. strong b. weak c. electromagnetic d. gravitational A

**physics**

please check these: A concave mirror with a focal length of 10.0 cm creates a real image 30.0 cm away on its principal axis. How far from the mirror is the corresponding object? a. 20cm b. 15cm c. 7.5cm d. 5.0cm B A diffraction grating that contains 650 472 lines/m is ...

**KC**

I have an assignment to discuss what scientists are doing to reduce the g forces on astronauts and to come up with a g force problem of my own. Can you help?

**KC**

Is anyone aware of some good links to sites which discuss and explain G-Force? I've searched but haven't come up with anything very worthwhile.Something with practice problems would be great. Thanks!

**physics**

according to Lenz's law, the magnetic field of an induced current in a conductor will a. enhance the applied field b. heat the conductor c. increase the potential difference d. oppose a change in the applied magnetic field i think D

**physics**

check which of the following modifications to a solenoid would be most likely to decrease the strength of its magnetic field? a. removing its iron rod core and increasing the number of coils b. increasing the current and reducing the number of coils c. reducing the number of ...

**physics**

then it's A?

**physics**

drwls said this is wrong but i don't know what's correct the enregy gained by electrons as they are accelerated by an electric field is a. greater than the average loss in energy due to collissions b. equal to the avergae loss in energy due to collissions c. less than ...

**physics**

thanks!

**physics**

please check these 3: if the batteries in a portable CD player provide a terminal voltage of 12 V, what is the potential difference across the entire CD player? a. 3.0 V b. 4.0 V c. 6.0 V d. 12 V D two resistors having the same resistance value are wired in parallel. how does ...

**physics**

i'm still getting C as the answer to this one drwl said its wrong When a positive charge moves in the direction of the electrical field, what happens to the electrical potential energy associated with the charge? a. increase b. decreases c. remains the same d. increases ...

**physics**

ok, :)

**physics**

nevermind i think its A can you check that?

**physics**

i can not find the correct answer for this one i got D but someone siad its wrogn electric field strength depends on a. charge and distnace b. charge and mass c. Coulomb constant and mass d. elementary charge and radius

**physics**

If atmospheric refraction did not occur, how would the apparent time of sunrise and sunset be changed? a. both would be later b. both would be earlier c. sunrise would be later, and sunset would be earlier d. sunrise would be earlier, and sunset would be later C drwls told me ...

**Physics**

what would be the appropriate answer choice for this question: If the batteries in a portable CD player provide a terminal voltage of 12 V, what is the potential difference across the entire CD player? a. 3.0 V b. 4.0 V c. 6.0 V d. 12 V thanks alot guys

**physics**

please check these for me: When a positive charge moves in the direction of the electric field, what happens to the electrical potential energy associated with the charge? a. it increases b. it decreases c. it remains the same d. it sharply increases, and then decreases C A ...

**physics**

please check these for me: If atmospheric refraction did not occur, how would the apparent time of sunrise and sunset be changed? a. both would be later b. both would be earlier c. sunrise would be later, and sunset would be earlier d. sunrise would be earlier, and sunset ...

**French Cuisine (Check)**

wow, it sounds really good but i think there might be a few spelling or grammatical errors, i found one:like 'seamed' which should be 'seemed'

**physics**

please check these for me: What is the wavelength of microwaves of 3.0*10^9 Hz frequency? a. 0.050m b. 0.060m c. 0.10 m d. 0.20 m C If a light ray strikes a flat mirror at an angle of 30deg from the normal, the ray will be reflected at an angle of a. 30deg from the mirror'...

**physics**

pleaase help me with this, i'm very bad in physics, and i mostly don't understand any of this stuff...can anyone explain as well as show me how to do this Monochromatic light from a helium-neon laser (wavelength=632.8 nm) shines at a right angle onto the surface of a ...

**physics**

how would i go about solving this problem? what formula shoud i use? can you please show me in steps how to do this, thanks a lot: The critical angle of refraction for calcite is 68.4degrees when it forms a boundary with water. Use this information to determine the speed of ...

**History**

the confederates also thought that if they had a choice to be a united nation, they also had a choice to leave it.

**MATH**

11/5 is an improper fraction, once you divide it, it will become a mixed number like MS.Sue said, 2 1/5

**physics**

please help: A repelling force occurs between two charged objects when the charges are of a. unlike signs b. like signs c. equal magnitude d. unequal magnitude

**physics**

here is my problem: a concave mirror forms a real image at 17.0 cm from the mirror surface along the principal axis. if the corresponding object is at a distance of 36.0 cm, what is the mirror's focal length? here's my work: 1/f = 1/v + 1/u where f=focal length=? u= -...

**physics**

please check these: a laser can be used a. to treat glaucoma b. to measure distance c. to read bar codes d. all of the above D in a laser, all of the following forms of energy can be converted into coherent light except a. chemical energy b. electrical energy c. light d. ...

**physics**

here is my problem: a concave mirror forms a real image at 17.0 cm from the mirror surface along the principal axis. if the corresponding object is at a distance of 36.0 cm, what is the mirror's focal length? here's my work: 1/f = 1/v + 1/u where f=focal length=? u= -...

**physics**

here is my problem: a concave mirror forms a real image at 17.0 cm from the mirror surface along the principal axis. if the corresponding object is at a distance of 36.0 cm, what is the mirror's focal length? here's my work: 1/f = 1/v + 1/u where f=focal length=? u= -...

**physics**

so Tf is 84.70?

**physics**

find the final equilibirum temperature when 10.0 g of milk at 10.0degC is added to 1.60*10^2 g of coffee with a temperatrure of 90.0degC. Assume the specific heats of coffee and milk are the same as for water (Cp,w=4.19J/g*degC) and disregard the heat capacity of the container...

**physics**

can you please show me?

**physics**

here is my question: A bullet with a mass of 6.00 g is fired through a 1.25 kg block of wood on a frictionless surface. The initial speed of the bullet is 896 m/s, and the speed of the bullet after it exits the block is 435 m/s. At what speed does the block move after the ...

**physics**

A certain radio wave has a frequency of 2.0 * 10^6 Hz. what is its wavelength?

**history**

so its A

**KC**

Great! thanks a lot.

**KC**

When a plane experiences a decrease in weight must there also be decrease in lift? I'm thinking the answer is yes in order to maintain equilibrium.

**Brock**

An object creates an inverted, virtual image, 3 cm tall, 10 cm from a converging mirror with a focal length of 15 cm. Where is the object located? How tall is it? I didn't think mirrors created inverted virtual images...

**Physics**

A box slides down a 30.0 degree ramp with an acceleration of 1.20 m/s^s Determine the coefficent of kinetic friction between the box and the ramp How on earth do I do this with only this amount of information???

**Physics**

Yah i got another question a large crate is placed on the bed of a truck but is not tied down as the truck accelerates forward the crate slides across the bed until it hits the tailgate explain what causes this i'm completley lost

**Physics**

An object thrown into the air stops at the highest pooint in its path is it in equilbrium at this point explain? I siad yes because it's moving for that one breif moment I wasn't sure or not so I'm asking to see if this is right