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physics makes the world go 'round
physics makes the world go 'round

Homework Help: Science: Physics

Recent Homework Questions About Physics

Post a New Question | Current Questions

physics
our class was given an extra credit assignment where we have to design a mobile that has both the net forces and torques = 0. i have all of the masses know i just don't know how to find radii. no two masses can be in the same position nor can they be at the center of mass...i;...
Friday, July 3, 2009 at 10:12pm

physics
explain the close relationship between magnetism and electricity? and How can electricity produce magnetism, and magnetism produce electricity.
Friday, July 3, 2009 at 3:24pm

physics
"A rod with length L , mass m and resistance R slides without friction down parallel conducting rail of negligible resistance . the rails are connected together at bottom, forming a conducting loop with the rod the plain of the loop makes angle Z wih horizontal , a uniform ver...
Friday, July 3, 2009 at 1:58pm

Physics
Is there a formula for heat of fusion equal 334kJ/kg for ice?
Tuesday, June 30, 2009 at 3:31pm

Physics
1 kg block of ice at 0 degrees celsius placed in cooler. How much heat will the ice remove as it melts to water at 0 degree celsius. I know the answer is 80kcal but don't know the math that backs up the answer-please help!
Tuesday, June 30, 2009 at 2:38pm

Physics
A PVC pipe that is one meter long is struck and the speed of sound is 345 m/s. What is the fundamental frequency (n=1) of the pipe when: a.The pipe is open at both ends? b.The pipe is closed at one end, open at the other?
Tuesday, June 30, 2009 at 12:06pm

physics
A magnet is plunged into and out of a coil of wire 2 times per second. This induces 5 volts. a- If the rate of motion changes so that the magnet is plunged in and out 6 times per second, what will be the new induced voltage? b- if the number of coils in the wire is doubled fro...
Monday, June 29, 2009 at 11:26pm

physics
if you have two 5 watt bulbs connected in series and then in parellel: which of these arrangements willa allow the other bulb to continue glowing if one of the bulbs are removed?
Monday, June 29, 2009 at 11:20pm

Physics
A PVC pipe that is one meter long is struck and the speed of sound is 345 m/s. What is the fundamental frequency (n=1) of the pipe when: a. The pipe is open at both ends? b. The pipe is closed at one end, open at the other?
Monday, June 29, 2009 at 10:12pm

Physics
The speed of sound in steel is 5000 m/s. What is the wavelength of the sound wave of 640 Hz in steel?
Monday, June 29, 2009 at 10:12pm

Physics
A potter’s wheel with rotational inertia of 45 kg m2, is spinning freely at 40 rpm. The potter drops a lump of clay onto the wheel where it sticks a distance 1.2 m from the rotational axis at the wheel’s center. If the subsequent angular speed of the wheel is 32 rpm, what is t...
Monday, June 29, 2009 at 8:14pm

Physics
A ladder of weight 200 N and length 10 m leans against a smooth wall with no friction. A firefighter of weight 600 N climbs a distance x up the ladder (x goes from the bottom of the ladder to the firefighter’s feet). The coefficient of friction between the ladder and the floor...
Monday, June 29, 2009 at 8:13pm

Physics
An 8 g bullet is shot into a 4.0 kg block, at rest on a frictionless horizontal surface. The bullet remains lodged in the block. The block moves into a spring and compresses it by 9.4 cm. The spring constant is 1000 N/m. What is the initial velocity of the bullet?
Monday, June 29, 2009 at 8:13pm

physics
what is the distance traveled by a vehicle in 12 minutes, if it's speed is 35km/h? And the answer I got was 7km but I got it wrong. Please help!
Monday, June 29, 2009 at 3:47pm

Physics
A small block on a frictionless horizontal surface has a mass of 2.50×10−2 Kg. It is attached to a massless cord passing through a hole in the surface. The block is originally revolving at a distance of 0.300 m from the hole with an angular speed of 1.75 rad/s. The cord ...
Thursday, June 25, 2009 at 11:59pm

Physics
A large turntable rotates about a fixed vertical axis, making one revolution in 6.00 s. The moment of inertia of the turntable about this axis is 1200 kg * mg^2. A childe of mass 40.0 kg, initually staning at the center of the turntable, runs out along a radius. What is the an...
Thursday, June 25, 2009 at 11:56pm

Physics
A uniform 250 N ladder rests against a perfectly smooth wall, making a 35 degree angle with the wall. (a) find the normal forces that the wall and the floor exert on the ladder. B) what is the friction force on the ladder at the floor?
Thursday, June 25, 2009 at 11:12pm

Physics
A large turntable rotates about a fixed vertical axis, making one revolution in 6.00 s. The moment of inertia of the turntable about this axis is 1200 kg * mg^2. A childe of mass 40.0 kg, initually staning at the center of the turntable, runs out along a radius. What is the an...
Thursday, June 25, 2009 at 10:44pm

Physics
Calculate the angular momentum and kinetic energy of a solid uniform sphere with a radius of 0.120 m and a mass of 14.0 kg if it is rotating at 6.00 rad/s about an axis through its center..
Thursday, June 25, 2009 at 10:25pm

Physics
A certain type of propeller blan can be modeled as a thin uniform bar 2.50 m long and of mass 24.0 kg that is free to rotate about a frictionless axle perpendicular to the bar at its midpoint. if a technician strikes this blade with a mallet 1.15 m from the center with a 35.0 ...
Thursday, June 25, 2009 at 8:56pm

Physics
We can roughly model a gumnastic tumbler as a uniform solid cylinder of mass 75 kg and diameter 1.0 m. If the tumbler rolls forward at .50 rev/s. A) how much total kinetic energy does he have and B) what percent of his total kinetic enery is rotational?
Thursday, June 25, 2009 at 8:51pm

physics
A girl of mass 60 kg throws a ball of mass 0.8 kg against a wall. The ball strikes the wall horizontally with a speed of 11 m/s, and it bounces back with this same speed. The ball is in contact with the wall 0.05 s. What is the average force exerted on the wall by the ball? A...
Wednesday, June 24, 2009 at 11:23pm

physics help!!!
the volume occupied by 1kg of water at 100C and atmospheric pressure changes from 1L in the liquid phase to 1700L in the vapor phase. evaluate the difference in internal energy of 1kg of water vapor and 1kg of liquid water at the normal boiling point: So i have the equation is...
Wednesday, June 24, 2009 at 10:27pm

physics- response to bobpursley
which is false? Consider the following processes: I. Energy flows as heat from a hot object to a colder object II. Work is done on a system and an equivalent amount of energy is rejected as heat by the system III. Energy is absorbed as heat by a system and an equivalent amount...
Wednesday, June 24, 2009 at 8:48pm

Physics
An object is thrown upwards with a speed of 14.0 m/s. How long does it take to reach its maximum height
Wednesday, June 24, 2009 at 8:07pm

physics
which is false? Consider the following processes: I. Energy flows as heat from a hot object to a colder object II. Work is done on a system and an equivalent amount of energy is rejected as heat by the system III. Energy is absorbed as heat by a system and an equivalent amount...
Wednesday, June 24, 2009 at 7:42pm

physics
Which of the following processes leads to a change in entropy of zero for the system undergoing the process? Non-cyclic isobaric (constant pressure) Non-cyclic isochoric (constant volume) Any closed cycle
Wednesday, June 24, 2009 at 5:28pm

Physics
Two identical perfectly smooth 71.2 N bowling balls 21.7 cm in diameter are hung together from the same hook by two massless wires. The bowling ball are just in contact with one another, and the angle between the two wires is 50 degrees. What is the force that one bowling ball...
Wednesday, June 24, 2009 at 1:49pm

physics
Use R = 8.2 × 10–5 m3 atm/mol K and NA = 6.02 × 1023 mol–1. The approximate number of air molecules in a 1 m3 volume at room temperature (300 K) and atomospheric pressure is:
Wednesday, June 24, 2009 at 8:42am

Physics
I had to graph the following data and find the slope: Normal Force: Frictional Force: 0 0 2.0 0.6 6.0 1.8 9.0 2.7 10.0 3.0 The slope was 0.30. The question that I am confused on is what does this graph's slope represent?
Wednesday, June 24, 2009 at 1:34am

physics repost
A quantity of an ideal gas is compressed to half" its initial volume. The process may be adiabatic, isothermal or isobaric. Rank those three processes in order of the work required of an external agent, least to greatest. doesn't adiabatic mean no work, so it would be the leas...
Tuesday, June 23, 2009 at 11:01pm

physics
A quantity of an ideal gas is compressed to half" its initial volume. The process may be adiabatic, isothermal or isobaric. Rank those three processes in order of the work required of an external agent, least to greatest. doesn't adiabatic mean no work, so it would be the leas...
Tuesday, June 23, 2009 at 9:16pm

physics
A quantity of an ideal gas is compressed to half" its initial volume. The process may be adiabatic, isothermal or isobaric. Rank those three processes in order of the work required of an external agent, least to greatest. doesn't adiabatic mean no work, so it would be the leas...
Tuesday, June 23, 2009 at 6:07pm

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) please s...
Tuesday, June 23, 2009 at 4:20pm

Physics
If a cup is half full of ice, how long will it take to melt the ice in a microwave oven (1000 W) set on high? Also, if you did the above but added 100ml of ice cold water to the ice would this change the results of melt time?
Tuesday, June 23, 2009 at 3:17pm

Physics PLEASE
I'm trying to solve this problem Calculate (a) how long it took King Kong to fall straight down form the top of the Empire State Building (380 m high), and (b) his velocity just before "landing". My teacher said try and rearagne this equation for t X = Xo + Vo t + 2^-1 a t^2 s...
Tuesday, June 23, 2009 at 1:54pm

Physics PLEASE
I'm trying to solve this problem Calculate (a) how long it took King Kong to fall straight down form the top of the Empire State Building (380 m high), and (b) his velocity just before "landing". My teacher said try and rearagne this equation for t X = Xo + Vo t + 2^-1 a t^2 I...
Tuesday, June 23, 2009 at 11:38am

physics repost bobpursley
The energy given off by 300 grams of an alloy as it cools through 50°C raises the temperature of 300 grams of water from 30°C to 40°C. The specific heat of the alloy (in cal/g C ) is: i know Q=CpM(delta T) but what is what? Responses * physics - bobpursley, Monday, June 22, 20...
Monday, June 22, 2009 at 10:48pm

physics
The energy given off by 300 grams of an alloy as it cools through 50°C raises the temperature of 300 grams of water from 30°C to 40°C. The specific heat of the alloy (in cal/g C ) is: i know Q=CpM(delta T) but what is what?
Monday, June 22, 2009 at 5:15pm

Physics
A 1200 kg car is moving on the freeway at 65 mph. (A) find the magnitude of its momentum and its kinetic energy in SI units. (b) if a 2400 kg SUV has the same speed asthe 1200 kg car, how much momentum and kinetic energy does it have?
Monday, June 22, 2009 at 2:06pm

Physics
The engine of a motorboat delivers 30.0 kW to the propeller while the boat is moving at 15.0m/s. What would be the tension in the towline if the boat were being towed at the same speed? I know to use P=Fv and solve for F so P = 3000kN right because 1 kW = 1000 Watts... and v= ...
Monday, June 22, 2009 at 1:51pm

Physics
A 61 kg skier on level snow coasts 184 m to stop from a speed of 12.0 m/s (A) use the work energy principle to find the coefficient of kinetic friction between the skis and the snow. B) suppose a 75 kg skier with twice the starting speed coasted the same distance before stoppi...
Monday, June 22, 2009 at 1:36pm

Physics
a fun loving 11.4kg otter slides up a hill and then back down to the same place. If she starts up at 5.75 m/s and returns at 3.75 m/s, how much mechanical energy did she lose on the hill and what happened to that energy
Monday, June 22, 2009 at 1:05pm

physics
A piano wire has length L and mass M. If its fundamental frequency is f, its tension is: i got T=(lambda*f)^2m/L, but their answer is 4LMF^2 and i cant figure out how to get that
Sunday, June 21, 2009 at 7:29pm

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 ...
Saturday, June 20, 2009 at 9:06pm

Physics
A racecar driver in an 825-kg car accelerates from rest to a velocity of 21.5 m/s in 0.55 s. What is the net force acting on the car? I found out using A=v/t that the horizontal acceleration is 39.1 m/s^2. My problem now is this... Is the net force just F=ma? Or do I have to t...
Saturday, June 20, 2009 at 8:55pm

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...
Saturday, June 20, 2009 at 7:46pm

Physics
You are told that the volume of a sphere is given by V=(sqrt)d^3/4, where V is the volume and d is the diameter of the sphere. Is this equation dimensionally correct?
Saturday, June 20, 2009 at 7:03pm

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?
Saturday, June 20, 2009 at 1:02pm

Physics
The last stage in the fusion of hydrogen to form helium in the Sun involves the formation of an alpha particle (4He) from two 3He nuclei: 3He + 3He 4He + p + p The binding energy for 3He is 2.57 MeV per nucleon and that for 4He is 7.07 MeV per nucleon. Calculate the amount of ...
Saturday, June 20, 2009 at 10:02am

Physics
Would someone check this please? A circular loop of wire of radius 0.10 m and of resistance 2.0 x 10^−3 ohms is in a region where there is a uniform magnetic field B. The field is at 30deg to the normal to the plane of the wire loop as shown in Figure 3. The magnitude of...
Saturday, June 20, 2009 at 8:01am

Physics PLEASE
Of course you have to rearrange it X -Xo = (V-Vo)(V+Vo)/2a (X-Xo)2a = (V-Vo)(V+Vo) 2 a (X-Xo) = V^2-Vo^2 ok to go from the first line to the second line you multiply by 2a I agree but what allows you to just put parenthsess around the X-Xo Thank You!
Friday, June 19, 2009 at 10:38pm

Physics Please
You want to show that V^2 - Vo^2 = 2 a (X - Xo) first rewrite that as: (V-Vo)(V+Vo) = 2a (X-Xo) now your average velocity during the interval = (V+Vo)/2 so X = Xo + t(V+Vo)/2 but V = Vo + a t so t = (V-Vo)/a so X = Xo +(V-Vo)(V+Vo)/2a we are there. -------------------- but wou...
Friday, June 19, 2009 at 7:13pm

Physics PLEASE
I'm trying to derive the formula v^2 = v0^2 + 2a(x-x0) were zeros are subscripts my book tells me to derive it this way use the definition of average velocity to derive a formula for x use the formula for average velocity when constant acceleration is assumed to derive a formu...
Friday, June 19, 2009 at 10:39am

physics please!
A 0.21 kg block oscillates back and forth along a straight line on a frictionless horizontal surface. Its displacement from the origin is given by x = (16 cm)cos[(16 rad/s)t + π/2 rad] What force, applied to the block by the spring, results in the given oscillation? why c...
Friday, June 19, 2009 at 8:49am

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