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April 23, 2014

Homework Help: Science: Physics

Recent Homework Questions About Physics

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physics
Calculate the percentage of Earth’s gravitational force on the ISS astronauts while orbiting at an altitude of 248 miles above Earth’s surface.
Tuesday, January 28, 2014 at 4:56pm

Physics
mh
Tuesday, January 28, 2014 at 4:48pm

physics
sin inverse of .032
Tuesday, January 28, 2014 at 4:44pm

Physics
I will assume the inclined block wins and slips down the hill Force up on inclined block = T force down slope on inclined block = 28 (9.81 )sin 53 - 28 (9.81)(.9)cos53 a = acceleration down slope 28 a = 28 (9.81 )sin 53 - 28 (9.81)(.9)cos53 - T Force down on hang mass = m g = ...
Tuesday, January 28, 2014 at 3:31pm

Physics
A copper sheet of thickness 2.49 mm is bonded to a steel sheet of thickness 1.51 mm. The outside surface of the copper sheet is held at a temperature of 100.0°C and the steel sheet at 24.1°C. a) Determine the temperature (in °C) of the copper-steel interface. b) ...
Tuesday, January 28, 2014 at 3:24pm

physics
wires are 60 degrees from vertical so T cos 60 = 110 T (1/2) = 110 T = 220 N
Tuesday, January 28, 2014 at 3:10pm

Physics
A block of mass m1 = 28 kg rests on a wedge of angle θ = 53∘ which is itself attached to a table (the wedge does not move in this problem). An inextensible string is attached to m1, passes over a frictionless pulley at the top of the wedge, and is then attached to ...
Tuesday, January 28, 2014 at 2:56pm

physics
a framed painting weighs 220 newtons. the 2 wires support an angle of 120 degrees with each other. what are the tensions on the wire?
Tuesday, January 28, 2014 at 2:45pm

physics
A block of mass m1 = 28 kg rests on a wedge of angle θ = 53∘ which is itself attached to a table (the wedge does not move in this problem). An inextensible string is attached to m1, passes over a frictionless pulley at the top of the wedge, and is then attached to ...
Tuesday, January 28, 2014 at 2:27pm

physics
B>C>A>D
Tuesday, January 28, 2014 at 2:14pm

physics
h = 3.0 + 2.58t - 4.9t^2 h=0 when t=1.08883 v = 2.58 - 9.8*1.08883 = -8.09 max h(0.263) = 3.34 Hmm. the max height seems kinda low, given that he started at 3.0 m up. Better double-check my math.
Tuesday, January 28, 2014 at 1:08pm

physics
A diver springs upward with an initial speed of 2.58 m/s from a 3.0-m board. (a) Find the velocity with which he strikes the water.(b) What is the highest point he reaches above the water?
Tuesday, January 28, 2014 at 12:35pm

physics 1
6700t - 6t^2 = 0 t = 1116.66 9700(1116.66) + a/2 (1116.66^2) = 0 a = -17.37 m/s^2
Tuesday, January 28, 2014 at 12:01pm

physics 1
1/2 (.386)t^2 + 1/2 (.359)t^2 = 88.7 .745t^2 = 177.4 t = 15.43 seconds to impact so, George rode .5(.386)(15.43^2) = 45.95 m
Tuesday, January 28, 2014 at 11:56am

physics 1
In an historical movie, two knights on horseback start from rest 88.7 m apart and ride directly toward each other to do battle. Sir George's acceleration has a magnitude of 0.386 m/s2, while Sir Alfred's has a magnitude of 0.359 m/s2. Relative to Sir George's ...
Tuesday, January 28, 2014 at 11:48am

physics 1
Two rockets are flying in the same direction and are side by side at the instant their retrorockets fire. Rocket A has an initial velocity of +6700 m/s, while rocket B has an initial velocity of +9700 m/s. After a time t both rockets are again side by side, the displacement of...
Tuesday, January 28, 2014 at 11:44am

physics
Assuming we can ignore the mass and motion of the spring, then we need to conserve momentum 10(3) = 15v
Tuesday, January 28, 2014 at 11:42am

Physics
A 70 kg person is at the top of a 10 m tall slide. Ignoring friction, what is his or her speed at the halfway point where he or she is 5 m from the bottom of the slide? What is his or her speed at the bottom of the slide?
Tuesday, January 28, 2014 at 11:33am

Physics
A 70 kg person is riding on a frictionless skateboard at 5 m/s. A friend facing him throws a 5 kg ball toward him at 20 m/s. What is his final speed after catching the ball?
Tuesday, January 28, 2014 at 11:32am

Physics 2
I think you'd better get out of physics. If you can't pay enough attention to distinguish "column" from "Coulomb" the details of solving problems is way past your pay grade.
Tuesday, January 28, 2014 at 11:21am

physics
A cart is driven by a large propeller or fan, which can accelerate or decelerate the cart. The cart starts out at the position x = 0 m, with an initial velocity of + 3.3 m/s and a constant acceleration due to the fan. The direction to the right is positive. The cart reaches a...
Tuesday, January 28, 2014 at 11:13am

PHYSICS
0,0000016
Tuesday, January 28, 2014 at 10:50am

PHYSICS
0,0000016
Tuesday, January 28, 2014 at 10:50am

physics
A 10.0 kg cart and a 15 kg cart are locked together with a compressed spring between them. They are then released so that the spring pushes the two carts apart. The 10.0 kg cart is moving at 3.0 m/s afterward. How fast is the 15 kg cart moving
Tuesday, January 28, 2014 at 10:48am

physics 1
vf^2=2ad you know vf, d, solve for a. vf=at solve for time t.
Tuesday, January 28, 2014 at 10:43am

physics 1
The left ventricle of the heart accelerates blood from rest to a velocity of + 24.8 cm/s. (a) If the displacement of the blood during the acceleration is + 2.97 cm, determine its acceleration (in cm/s2). (b) How much time does blood take to reach its final velocity?
Tuesday, January 28, 2014 at 10:40am

physics
steel http://www.physicsforum_search_20140419s​.com/showthread.php?t=596391
Tuesday, January 28, 2014 at 10:39am

physics
That force East is opposed by Earth. Actually, the motorcycle is starting to increase the speed of rotation of Earth,but is is very massive, and the change in rotation is very, very small. Since the Earth is opposing this motion, it is pushing back on the motorcycle westward, ...
Tuesday, January 28, 2014 at 10:37am

Physics
you want a mechanical advantage of 100*9.8/250 MA= length/height = 9800/250 solve for lenght
Tuesday, January 28, 2014 at 10:30am

physics
A 257kg motor cycle and rider accelerate from rest and reach a velocity of 20 meters per second west. The motor cycle wheels exert an average force 710N east of the road.Explain how the force directed east causes the motorcycle to accelerate west
Tuesday, January 28, 2014 at 10:30am

physics
depends on the solid, and the temperature range. Most typically, expand.
Tuesday, January 28, 2014 at 10:27am

physics
Does an solid expand or contract as the temperature rises?
Tuesday, January 28, 2014 at 10:14am

Physics
An inclined plane is used to raise a 100 kg box to a height of 5 m. How long must the inclined plane be if a force of 250 N is used to push the box up the inclined plane?
Tuesday, January 28, 2014 at 10:01am

physics
1. Where does sound travel fastest? water, salt water, steel, or wood 2. Does sound travel faster in salt water than water?
Tuesday, January 28, 2014 at 9:59am

Physics
v=0.575m/s
Tuesday, January 28, 2014 at 8:48am

physics
calculate the mass of air in a room measuring 5m*8m*10m if the density of air is 1.3kg/m cube
Tuesday, January 28, 2014 at 8:24am

Physics 2
2 spheres of equal diameters have a positive 15 micro column and negative 10 micro column charge if they are place 5 cm apart what would be the force of attraction between them.
Tuesday, January 28, 2014 at 6:40am

Physics
vertical speed observed = -37.9 sin 50.8 = -29.4 m/s how far did it fall to reach -29.4 m/s? v = -g t -29.4 = -9.81 t t = 2.99 s d = 4.9 t^2 = 4.9 (2.99)^2 = 43.9 so it reached 43.9 + 22.5 = 66.42 m vertical speed at ground? fell from 66.42 m 66.42 = 4.9 t^2 t = 3.68 s v = -g ...
Tuesday, January 28, 2014 at 5:42am

Physics Help - Use Damon's Answer
Go with Damon - I switched the a and the t.
Tuesday, January 28, 2014 at 5:19am

Physics Help
39 km/hr = 10.83 m/s s = Vi*t + 1/2 at^2 25 = 10.83t + .5 at^2 v = Vi + at 10.83 + at = 0 so, t = 2.35s a = -4.46 m/s^2
Tuesday, January 28, 2014 at 5:18am

Physics Help
39,000 m/3600 s = 10.83 m/s average speed during braking = 10.83/2 = 5.42 25 = 5.42 t t = 25/5.42 = 4.62 seconds to stop v = Vi + a t 0 = 10.83 + a (4.62) a = -2.34 m/s^2 1/4 g is not an unreasonable deacceleration
Tuesday, January 28, 2014 at 5:16am

Physics Help
You're driving at 39km/h , when the traffic light 25m away turns yellow. I need to find the constant acceleration required to stop at the light, the stopping time, and weather the acceleration is reasonable. I know how to find the average and instantaneous acceleration, ...
Tuesday, January 28, 2014 at 12:54am

Physics
A small rocket is fired in a test range. It rises high into the air and soon runs out of fuel. On the way down it passes near an observer (sitting in a 22.5-m-high tower) who sees the rocket traveling at a speed of 37.9 m/s and moving in a vertical plane at an angle of 50.8&...
Tuesday, January 28, 2014 at 12:00am

Physics
L = V/F = 489*10^-9 m. 3*10^8/4.89*10^-7 = 6.13*10^14 Hz.
Monday, January 27, 2014 at 11:18pm

physics
a=v^2/r
Monday, January 27, 2014 at 11:13pm

Physics
A baggage carousel at an airport is rotating with an angular speed of 0.397 rad/s when the baggage begins to be loaded onto it. The moment of inertia of the carousel is 2440 kg·m2. Ten pieces of baggage with an average mass of 16.5 kg each are dropped vertically onto ...
Monday, January 27, 2014 at 10:40pm

Physics
A train moving at a constant speed of 61.0 km/h moves east for 35.0 min, then in a direction 50.0° east of due north for 10.0 min, and then west for 49.0 min. What is the average velocity of the train during this run? What is the magnitude of that velocity? What is the ...
Monday, January 27, 2014 at 10:39pm

Physics
YOu know the initial angular moentum, the final moment of inertia= initial + 10mass*r^2 solve the conservation of angular momentum problem.
Monday, January 27, 2014 at 10:15pm

Physics
you know hf, distance final, df, and the ratio of Vverticalfinal to vhoriz final frm the landing angle. This is going to be an exercise in math. Lets work it backwards. Assume V as the launching velocity on the ledge, as if they sent a package to you. hf=hi+ViSin75*time-4.9t^2...
Monday, January 27, 2014 at 10:14pm

Physics
A baggage carousel at an airport is rotating with an angular speed of 0.397 rad/s when the baggage begins to be loaded onto it. The moment of inertia of the carousel is 2440 kg·m2. Ten pieces of baggage with an average mass of 16.5 kg each are dropped vertically onto ...
Monday, January 27, 2014 at 10:10pm

Physics
A stationary bicycle is raised off the ground, and its front wheel (m = 1.70 kg) is rotating at an angular velocity of 21.9 rad/s (see the figure). The front brake is then applied for 1.35 s, and the wheel slows down to 4.47 rad/s. Assume that all the mass of the wheel is ...
Monday, January 27, 2014 at 10:10pm

Physics
An alpine rescue team is using a slingshot to send an emergency medical packet to climbers stranded on a ledge. (height=252 m, horizontal distance=416 m, landing angle= 75° below the horizontal). What should be the launch speed from the slingshot? What is the launch angle...
Monday, January 27, 2014 at 10:04pm

Physics
and the question/
Monday, January 27, 2014 at 10:01pm

PHYSICS
assume all the charge is at the center on each rod. F=kQQ/distancefromcenters^2
Monday, January 27, 2014 at 10:00pm

physics
first find the terminal velocity distance=1/2 a t^2 solve for a then, vf= at Then solve for the braking acceleration 0= vabove*2 +2ad solve for a
Monday, January 27, 2014 at 9:57pm

physics
according to recent typical test data, a Ford Focus travels 0.23 mi in 19 seconds, starting from rest. The same car, when braking from 59.0mph on dry pavement, stops in 141 ft. Assume constant acceleration in each part of its motion, but not necessarily the same acceleration ...
Monday, January 27, 2014 at 9:50pm

physics
That doesn't work out to the correct answer. I worked it the same as you but I get 1.4 instead of 2.4.
Monday, January 27, 2014 at 9:46pm

Physics
Draw a diagram of forces. Then balance all forces on the stick.
Monday, January 27, 2014 at 9:46pm

physics
3
Monday, January 27, 2014 at 9:43pm

physics
Fr = (Vs-Vc)/(Vs+Va)*Fa Fc = (343-32.3)/(343+60.7)*521 = 401 Hz= Freq. heard by car driver.
Monday, January 27, 2014 at 9:42pm

PHYSICS
Two identical teflon rods are 10 centimeters long and rubbed with fur so that they each have a total negative charge of 20 microCoulombs that is uniformly distributed along their length. They are arranged along the same axis, with their ends 5 centimeters apart. What is the ...
Monday, January 27, 2014 at 9:41pm

Physics
An alpine rescue team is using a slingshot to send an emergency medical packet to climbers stranded on a ledge. (height=252 m, horizontal distance=416 m, landing angle= 75° below the horizontal).
Monday, January 27, 2014 at 9:26pm

physics
Vector has a magnitude of 122 units and points 37.0 ° north of west. Vector points 64.0 ° east of north. Vector points 17.0 ° west of south. These three vectors add to give a resultant vector that is zero. Using components, find the magnitudes of (a) vector and (b...
Monday, January 27, 2014 at 8:57pm

physics
A jogger travels a route that has two parts. The first is a displacement of 2.15 km due south, and the second involves a displacement that points due east. The resultant displacement + has a magnitude of 3.95 km. (a) What is the magnitude of , and what is the direction of + as...
Monday, January 27, 2014 at 8:46pm

physics
A car is being pulled out of the mud by two forces that are applied by the two ropes shown in the drawing. The dashed line in the drawing bisects the 30.0° angle. The magnitude of the force applied by each rope is 2900 newtons (N). (a) How much force would a single rope ...
Monday, January 27, 2014 at 8:38pm

physics
Three deer, A, B, and C, are grazing in a field. Deer B is located 63.4 m from deer A at an angle of 50.8 ° north of west. Deer C is located 76.7 ° north of east relative to deer A. The distance between deer B and C is 96.7 m. What is the distance between deer A and C?
Monday, January 27, 2014 at 8:36pm

Physics
A meter stick balances at the 50.0-cm mark. You tie a 20N weight at the 20cm mark. Where should a 30N weight be placed so the meter stick will again be balanced?
Monday, January 27, 2014 at 8:24pm

Physics
T=2PIsqrt(l/g) l/g= T^2/2PI g= l*2PI/l use 3.14159 for pi or better.
Monday, January 27, 2014 at 8:21pm

Physics
Xo = 50 m/s. = Hor. component. Y = 42 m/s = Ver. component. Tot. velocity = sqrt(50^2+42^2)=65.3 m/s
Monday, January 27, 2014 at 8:21pm

Physics
t
Monday, January 27, 2014 at 8:20pm

physics
hf=hi+vi*t-1/2 g t^2 first, I am wondering is the 30 degrees above horizontal, or below horizonal. I will work it as ABOVE horizontal. vi vertical= 40*sin30=20m/s -25=0+20t-g/2 t^2 solve for t t^2-40t/g -25-0 t= 20/g +- sqrt (400/g^2 + 25) tearth=you do it. tMars = you do it, ...
Monday, January 27, 2014 at 8:19pm

Physics
In Cambridge, England, a seconds pendulum is 0.9942 m long. What is the free-fall acceleration in Cambridge? (Use 4 significant figures in your answer.)
Monday, January 27, 2014 at 8:19pm

Physics
Graphically this is so easy, and that is exactly how pilots would do it. Put the wind at 100 NE, then on the end of that, take a vector from that point 600 in length, use a compass to draw an arc until it intercepts N. Then that is the direction. Want to do it analytically? ...
Monday, January 27, 2014 at 8:11pm

Physics
0.5g*t^2 = 90 m. 4.9t^2 = 90 t^2 = 18.37 t = 4.29 s. Distance = Xo*t = 50m/s * 4.29s=214.3 m. V = Vo+g*t = 0 + 9.8*4.29 = 42 m/s.
Monday, January 27, 2014 at 8:09pm

Physics
A pilot flies a plane at a speed of 600 km/h with respect to the surrounding air. A wind is blowing to the northeast at a speed of 100 km/h. In what direction must the plane be aimed so that the resulting direction of the plane is due north?
Monday, January 27, 2014 at 7:59pm

physics
I will be happy to check your thinking on this. on the horzontal force, you need to break that into normal up the ramp and up the ramp components.
Monday, January 27, 2014 at 7:48pm

physics
A 6.30kg block is pushed 9.50m up a smooth 35.0∘ inclined plane by a horizontal force of 77.0N . If the initial speed of the block is 3.15m/s up the plane. What is the initial kinetic energy of the block, the work done by the 77.0N force, the work done by gravity, the ...
Monday, January 27, 2014 at 7:46pm

Physics
isn't this a formula? period=1/freq=2PI sqrt (l/g)
Monday, January 27, 2014 at 7:39pm

physics
This would make an excellent graphic solution...I am certain you have done distance, velocity graphs. If you want to nerd it out in math, work it in steps. 1. figure speed at 4.9 seconds, then that is te speed at 8 seconds.. 2. how far? figure the distance while accelerating, ...
Monday, January 27, 2014 at 7:38pm

physics
Two cars start from rest at a red stop light. When the light turns green, both cars accelerate forward. The blue car accelerates uniformly at a rate of 5.5 m/s2 for 4.9 seconds. It then continues at a constant speed for 6.7 seconds, before applying the brakes such that the car...
Monday, January 27, 2014 at 7:25pm

Physics
Find the length of a pendulum that oscillates with a frequency of 0.37 Hz.
Monday, January 27, 2014 at 6:54pm

physics
a projectile is ejected from a 25 m high tower with a velocity of 40 m/s at an angle of 30 degrees to the horizontal first on Earth and then on Mars. What is the ratio of the time taken to hit the ground on Mars compared to Earth? (Assume gravity on mars = .38gEarth) The ...
Monday, January 27, 2014 at 6:49pm

Physics
1
Monday, January 27, 2014 at 6:39pm

physics
hat is the wavelength of an earthquake that shakes you with a frequency of 12.5 Hz and gets to another city 90.0 km away in 12.0 s?
Monday, January 27, 2014 at 6:37pm

PHYSICS
Two identical teflon rods are 10 centimeters long and rubbed with fur so that they each have a total negative charge of 20 microCoulombs that is uniformly distributed along their length. They are arranged along the same axis, with their ends 5 centimeters apart. What is the ...
Monday, January 27, 2014 at 5:12pm

physics
i = V/R = 60/25 = 2.4 amps P = i v = 2.4*60 = 144 watts or Joules/second Joules into water = 144 t where t is in seconds 144 t = C (.5)(100-29) I do not recall C, specific heat of water in Joules/ kilogram deg centigrade
Monday, January 27, 2014 at 5:07pm

physics (clear answer)
vertical problem first Vi = 16 sin 38.5 = 9.96 m/s v = Vi - g t = 9.96 - 9.81 t h = Hi + Vi t - (1/2) g t^2 3 = 0 + 9.96 t - 4.9 t^2 4.9 t^2 - 9.96 t + 3 = 0 t = [ 9.96 +/- sqrt(99.2-58.8) ]/9.81 t = [9.96 +/- 6.36 ] /9.81 t = 1.66 seconds in air v = 9.96 - 9.81(1.66) = -6.36 ...
Monday, January 27, 2014 at 4:58pm

physics
An electric heater used to boil small amounts of water consists of a 25-Ω coil that is immersed directly in the water. It operates from a 60-V socket. How much time is required for this heater to raise the temperature of 0.50 kg of water from 29° C to the normal ...
Monday, January 27, 2014 at 4:56pm

physics (clear answer)
A golfer hits a shot to a green that is elevated 3 m above the point where the ball is struck. The ball leaves the club at a speed of 16.0 m/s at an angle of 38.5° above the horizontal. It rises to its maximum height and then falls down to the green. Ignoring air ...
Monday, January 27, 2014 at 4:37pm

physics
A tungsten wire has a radius of 0.077 mm and is heated from 20.0 to 1205 °C. The temperature coefficient of resistivity is α = 4.5 10-3 (C°)−1. When 110 V is applied across the ends of the hot wire, a current of 1.3 A is produced. How long is the wire? ...
Monday, January 27, 2014 at 4:36pm

Physics
4
Monday, January 27, 2014 at 4:21pm

URGENT Physics PLEASE help
1600 * 24 south 150 * 8 m = p/v = 200/.8
Monday, January 27, 2014 at 3:38pm

Please help with Physics Quickly
Impulse is integral F dt , change in momentum Impulse is average force times time of interaction Impulse = F t -------------------------- The way I think about it: I do not really use F = m a I think F = d/dt(mv) the rate of changer of momentum (By the way, that works even ...
Monday, January 27, 2014 at 3:34pm

Please help with Physics Quickly
1. How are impulse and momentum related? (Points : 1) Impulse is the change in momentum of an object. Momentum is the change in impulse acting on an object. Impulse and momentum are always equal in magnitude. Impulse and momentum are the same thing. Question 2. 2. Which of ...
Monday, January 27, 2014 at 2:32pm

URGENT Physics PLEASE help
5. A 1,600 kg car is moving south at 24 m/s. What is its momentum? (Points : 1) 66 kgm/s south 66 kgm/s north 38,000 kgm/s north 38,000 kgm/s south Question 6. 6. The velocity of a 150 kg cart changes from 6.0 m/s to 14.0 m/s. What is the magnitude of the impulse that acted on...
Monday, January 27, 2014 at 2:31pm

Physics
A diver springs upward from a board that is 3.20 m above the water. At the instant she contacts the water her speed is 11.4 m/s and her body makes an angle of 68.7 ° with respect to the horizontal surface of the water. Determine her initial velocity, both (a) magnitude and...
Monday, January 27, 2014 at 2:09pm

physics
Now wait a minute, your questions are really all the same question. The only difference is arithmetic. F = k Q1Q2 /r^2
Monday, January 27, 2014 at 1:37pm

physics
same old formula E = k Qe/r^2 N/C Qe = - 1.6*10^-19 Coulombs r = 3 * 10^-3 meters k = 9 * 10^9 N m^2/C^2 E is toward negative charge
Monday, January 27, 2014 at 1:35pm

physics
F * d = energy lost to friction = (1/2) m v^2 m g mu d = (1/2) m v^2 9.81 mu (8) = .5 (16) = 8 mu = 1/g = about .1
Monday, January 27, 2014 at 1:30pm

physics
E = k Q/r^2 direction away from Q since Q is positive
Monday, January 27, 2014 at 1:27pm

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