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April 23, 2014

Homework Help: Science: Physics

Recent Homework Questions About Physics

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Physics.
m v^2/r = 1.9 (2.8)^2/2.3 Newtons
Thursday, March 20, 2014 at 4:29am

Physics
Ac = v^2/r F = m Ac = m v^2/r = 80 (3.2^2)/2.4 = 341 N = 340 N to two figures
Thursday, March 20, 2014 at 4:27am

Physics
A Plane flies north at 215 km/h. A wind from the east blows at 69km/h. What is the plane's new velocity with respect to the ground in standard position
Wednesday, March 19, 2014 at 11:02pm

Science (Physics)
456
Wednesday, March 19, 2014 at 10:47pm

physics
Vo = 6.93 m/s[45.6o] Xo = 6.93*cos45.6 = 4.85 m/s Yo = 6,93*sin45.6 = 4.95 m/s. h = (Y^2-Yo^2)/2g = (0-4.95^2)/-19.6 = 1.25 m.
Wednesday, March 19, 2014 at 10:19pm

Physics
During a tennis serve, the ball goes from rest to approximately 32.1 m/s. The average power generated during the serve is equal to 2614 Watts. If the acceleration is constant during the serve, what is the magnitude of the force acting on the ball?(? N)
Wednesday, March 19, 2014 at 10:18pm

physics
A force in the +x-direction with magnitude F(x)=18.0N−(0.530N/m)x is applied to a 7.60kg box that is sitting on the horizontal, frictionless surface of a frozen lake. F(x) is the only horizontal force on the box. If the box is initially at rest at x=0, what is its speed ...
Wednesday, March 19, 2014 at 9:35pm

Physics
V^2 = Vo^2 + 2g*h = 0 at peak. Vo^2 - 19.6*16.6 = 0 Vo^2 = 325.4 Vo = 18.04 m/s = Speed at which ball was kicked.
Wednesday, March 19, 2014 at 9:03pm

Physics
Calculate the force of friction that keeps a 80-kg person sitting on the edge of a horizontal rotating platform when the person sits 2.4m from the center of the platform and has a tangential speed of 3.2m/s . Express your answer to two significant figures and include the ...
Wednesday, March 19, 2014 at 8:51pm

Physics.
Calculate the tension in a horizontal string that whirls a 1.9-kg toy in a circle of radius 2.3m when it moves at 2.8m/s on an icy surface. Express your answer to two significant figures and include the appropriate units
Wednesday, March 19, 2014 at 8:50pm

Physics!
Yes he's a Professor , I'm stumped and have no clue whats he asking.
Wednesday, March 19, 2014 at 8:47pm

Physics
assuming the cat had no air friction... momentum final=mv vf^2=vi^2+2gd or vf=sqrt (2gd) 55.8=3.9(sqrt(2gd) solve that for d.
Wednesday, March 19, 2014 at 8:33pm

Physics
A 3.9 kg cat falls out a window. Just before landing, the cat's momentum is equal to 55.8 kg m/s. How high was the window where the cat fell from?(?m)
Wednesday, March 19, 2014 at 8:30pm

physics
isnt flux equal to B times area? I dont have a clue what a circular surface means, I assume a disk.
Wednesday, March 19, 2014 at 8:17pm

Physics!
Rotating about a planet, or rotating about an internal axis? If about the planet, it the "outward" forces balance: gravity and centripetal force. If rotating about an axis a,b,c is wrong, and I have no idea what "in the traditional sense" means. If ...
Wednesday, March 19, 2014 at 8:16pm

Physics!
Consider someone in a rotating space habitat. The outward force felt by the person A.has no reaction counterpart B.is an interaction with Earth C.is a form of gravity D.is real in the traditional sense
Wednesday, March 19, 2014 at 8:07pm

physics
what is the magnetic flux of a magnetic field of 3.5 x 10 T lassing a given circular surface with radius 30 cm
Wednesday, March 19, 2014 at 8:01pm

Physics
I once was given a metal whiskey flask for being in my cousin’s wedding. When it got dented, I put in 1 gram of H2O (initially 21°C, just like the air filling the rest of the flask) and heated it up to boil the water. It popped the dent out. Assume the flask had a ...
Wednesday, March 19, 2014 at 8:00pm

physics
10000
Wednesday, March 19, 2014 at 7:48pm

Physics
Circumference = pi * 2r = 3.14 * 0.20 = 0.6283 m/rev. Va = 24m/s * 6.28rad/0.6283m = 240 rad/s = Angular velocity. V = 24m/s * 1rev/0.6283m * 60s/min = 2292 RPM.
Wednesday, March 19, 2014 at 7:23pm

Physics
Been there, done that
Wednesday, March 19, 2014 at 5:54pm

Physics
total mass = .5 + .005 = .505 kg potential energy = m g h = .505*9.81*.08 = .396 Joules that is Ke at bottom (1/2) (.505) v^2 = .396 v = 1.25 m/s momentum = m v = .505 * 1.25 = .633 kg m/s
Wednesday, March 19, 2014 at 5:53pm

Physics
I assume your 4.2 meters is vertical component of ramp since you did not give an angle. m g h = 11 * 9.81 * 4.2 = 453 Joules decrease in potential energy That goes in PE of spring (1/2) k x^2 = 453 250 x^2 = 906 x = 1.90 meters due to velocity k x = weight = 11*9.81 x due to ...
Wednesday, March 19, 2014 at 5:50pm

Physics
A 5.00-g bullet is fired into a 500-g block of wood suspended as a ballistic pendulum. the combined mass swings up to a height of 8.00 cm. What was the magnitude of the momentum of the combined mass immediately after the collision? Answer a. 0.394 kg·m/s b. 0.632 kg&...
Wednesday, March 19, 2014 at 5:48pm

Physics
A 5.00-g bullet is fired into a 500-g block of wood suspended as a ballistic pendulum. the combined mass swings up to a height of 8.00 cm. What was the magnitude of the momentum of the combined mass immediately after the collision?
Wednesday, March 19, 2014 at 5:47pm

Physics
Circumference = pi * 2r = 3.14 * 0.620 = 1.95 m/rev. 8.5*10^7m * 1rev/1.95m = 4.36*10^7 Revs = 43.6 Million Revs.
Wednesday, March 19, 2014 at 4:40pm

Physics
a. Y^2 = Yo^2 + 2g*h = 0 m/s @ max. ht. Yo^2 - 19.6*0.750 = 0 Yo^2 = 14.7 Yo = 3.83 m/s. = Initial ver. velocity. b. Y = Yo + g*Tr = 0 m/s @ max. ht. Y = 3.83 - 9.8Tr = 0 9.8Tr = 3.83 Tr = 0.3908 s. = Rise time. Dx=Xo * Tr = 5m/s * 0.3908s. = 1.95 m. From basket.
Wednesday, March 19, 2014 at 4:06pm

Physics
A 11 kg box slides 4.2 m down a frictionless ramp and then collides with a spring whose spring constant is 250 N/m. What is the maximum compression of the spring? I got 1.35 m but it is incorrect. Any help would be great!
Wednesday, March 19, 2014 at 3:51pm

Physics
You didn't convert the frequenzy from kKz to Hz. And don't forget to convert your answer to millimeter
Wednesday, March 19, 2014 at 3:34pm

Physics
Range = Vo^2*sin(2A)/g = 78 m. 34^2*sin(2A)/9.8 = 78 Solve for A.
Wednesday, March 19, 2014 at 2:33pm

Algebra Based Physics
A 2.50-kg steel ball strikes a massive wall at 10.0 m/s at an angle of θ = 60.0° with the plane of the wall. It bounces off the wall with the same speed and angle (see the figure below). If the ball is in contact with the wall for 0.224 s, what is the average force ...
Wednesday, March 19, 2014 at 2:28pm

Physics
All I'm looking for is confirmation that I correctly solved the problem. I know that I can use the formula: λ(wavelength) = v/f When I put in the numbers it gives me 5.666666666666667, which I then round up to 5.7. Is 5.7m the correct answer?
Wednesday, March 19, 2014 at 2:20pm

PHYSICS
See previous post: Mon,3-17-14,8:03 PM.
Wednesday, March 19, 2014 at 2:20pm

Physics question - I NEED HELP PLEASE
need rules of physics here. volume of water if trough is full = (1/2)(3)(5)(8) = 60 cubic metres from here on it is physics
Wednesday, March 19, 2014 at 2:18pm

Physics
Bats chirp at a high frequency which humans cannot hear. They use the echoes to detect small objects, such as insects, as small as one wavelength. If a bat were to emit a chirp at a frequency of 60.0 kHz and the speed of sound waves in the air are 340 m.s, what is the size in ...
Wednesday, March 19, 2014 at 2:15pm

physics question for damon (a clarification)
Hi Damon! You helped me out in this question yesterday (jiskha. com /display.cgi?id = 1395185605) and I was wondering why you added gravity when calculating the friction. Thanks for your help!
Wednesday, March 19, 2014 at 1:55pm

physics
A cylinder floats with its volume 3 cubic metre inside water. What is its total volume if its density 100 kg per cubic metre? Density of water is 1000 kg per cubic metre
Wednesday, March 19, 2014 at 11:17am

Physics
Prove that tanø is equal to U(k) when the block slides down the incline with a constant speed. (Use symbols, not numbers.)
Wednesday, March 19, 2014 at 9:38am

physics
Two cars start off a race with initial velocities u0 and v0, and travel in a straight line with uniform acceleration á and â. If the race ends in a dead beat, prove that the length s of the race is: s=(2(u_0-v_0)(u_0 â-v_0 á))/(â-á)^2
Wednesday, March 19, 2014 at 9:37am

physics hw
2250 N
Wednesday, March 19, 2014 at 9:03am

physics
20mcubic
Wednesday, March 19, 2014 at 8:44am

physics
A pitcher throws a 0.198-kg baseball, and it approaches the bat at a speed of 57.5 m/s. The bat does 85.1 J of work on the ball in hitting it. Ignoring air resistance, determine the speed of the ball after the ball leaves the bat and is 32.7 m above the point of impact.
Wednesday, March 19, 2014 at 6:49am

physics
The drawing shows a skateboarder moving at 6.93 m/s along a horizontal section of a track that is slanted upward by 45.6 ° above the horizontal at its end, which is 0.654 m above the ground. When she leaves the track, she follows the characteristic path of projectile ...
Wednesday, March 19, 2014 at 2:47am

Physics helpp please!
12.48
Wednesday, March 19, 2014 at 12:08am

simple physics
thankx
Tuesday, March 18, 2014 at 11:43pm

physics
A sign is hanging from the ceiling on two threads of equal length, which make an angle $\theta$ of 108.5 "degrees" with each other. What is the tension (in N) in each thread, assuming that the force of gravity acting on the sign is 46.5 N?
Tuesday, March 18, 2014 at 10:46pm

Physics
(Need Help Only For Last Question! I figured out the first two.) A car of mass m = 1130 kg is traveling down a θ = 11 degree incline. When the car's speed is v0 = 11 m/s, a mechanical failure causes all four of its brakes to lock. The coefficient of kinetic friction ...
Tuesday, March 18, 2014 at 10:32pm

Honors Physics
total energy=mgh+1/2 ke at top energy at booting= 1/2 m v^2 solve for v at kickoff, as energy at kickoff=total energy at top.
Tuesday, March 18, 2014 at 10:23pm

Physics
A 60 kg girl on a swing is pulled 1.5 meters back and then released. The girl oscillates at pi/3 radians per second. How far from equilibrium will the girl be in 4 seconds into the motion? How fast will she be moving at this location?
Tuesday, March 18, 2014 at 10:22pm

physics
The angle of incidence and the angle of refraction for light going from air into a material with a higher index of refraction are 69.9° and 39.6°, respectively. What is the index of refraction of this material?
Tuesday, March 18, 2014 at 10:17pm

Physics
m*g = 20 N. m = 20/g = 20/9.8 = 2.041 kg A. Work = 0.5m*Vo^2 - 0.5m*V^2 = mg*h 1.02*Vo^2 - 1.02*25^2 = 20*14.8 1.02Vo^2 - 637.5 = 290 1.02Vo^2 = 290 + 637.5 = 927.5 Vo^2 = 909.31 Vo = 30.15 m/s. B. h = (V^2-Vo^2)/2g = (0-30.15^2)/-19.6 = 46.38 m.
Tuesday, March 18, 2014 at 10:02pm

Physics
During a free kick at a soccer playoff game a 0.5 kg ball at the peak of the kick 16.6 m above the field had a kinetic energy of 35.4 J. How fast was the ball booted by the player on the field?
Tuesday, March 18, 2014 at 9:16pm

Honors Physics
0.5 kg ball at the peak of the kick 16.6 m above the field had a kinetic energy of 35.4 J. How fast was the ball booted by the player on the field?
Tuesday, March 18, 2014 at 9:15pm

Physics
If the work required to stretch a spring 4 feet beyond its natural length is 17 foot-pounds, how much work is needed to stretch it 14 inches beyond its natural length? Your answer must include the correct units. (You may enter lbf or lb*ft for ft-lb.)
Tuesday, March 18, 2014 at 9:14pm

Physics
concave
Tuesday, March 18, 2014 at 8:52pm

simple physics
normal force on floor = 750 sin 25 + 9.81 m friction force =.73(750 sin 25 + 9.81 m) so 750cos25 = .73(750 sin 25 + 9.81 m) solve for m
Tuesday, March 18, 2014 at 8:03pm

physics
Ratio = (331+0.6T1)/(331+0.6T2) = (331+0)/(331+60) = 0.847
Tuesday, March 18, 2014 at 7:57pm

simple physics
You push downward on a box at an angle 25° below the horizontal with a force of 750 N. If the box is on a flat horizontal surface for which the coefficient of static friction with the box is 0.73, what is the mass of the heaviest box you will be able to move?
Tuesday, March 18, 2014 at 7:33pm

PHYSICS
You are welcome. As always, check my arithmetic.
Tuesday, March 18, 2014 at 7:23pm

PHYSICS
thank you.
Tuesday, March 18, 2014 at 7:20pm

PHYSICS
Initial speed = 3 m/s acceleration constant during braking therefore average speed during stop = 3/2 = 1.5 m/s time to stop = t =7 m / 1.5 m/s = 4.67 seconds v = Vi +a t 0 = 3 + a(4.67) a = -0.643 m/s^2 F = m a F = 5 (.643) F = 3.21 Newtons F = mu (weight) 3.21 = mu (5)(9.81) ...
Tuesday, March 18, 2014 at 7:17pm

PHYSICS
A 5.00-kg box slides 7.00 m across the floor before coming to rest. What is the coefficient of kinetic friction between the floor and the box if the box had an initial speed of 3.00 m/s?
Tuesday, March 18, 2014 at 7:09pm

Physics
net force=total mass*a net force=9.4-.25(total mass)g then the first equation, solve for acceleartion a. tension on the second=masssecond*a+ .25*masssecond*g
Tuesday, March 18, 2014 at 6:51pm

Physics
A force of 9.4N pulls horizontally on a 1.2-kg block that slides on a rough, horizontal surface. This block is connected by a horizontal string to a second block of mass m2 = 2.00kg on the same surface. The coefficient of kinetic friction is μk = 0.25 for both blocks. ...
Tuesday, March 18, 2014 at 6:21pm

physics
1. 15 - 6 = 9 N. = Net force. 2. a = Fn/m = 9/3 = 3 m/s^2.
Tuesday, March 18, 2014 at 6:17pm

Physics
287 degrees Celsius
Tuesday, March 18, 2014 at 5:34pm

PHYSICS
Bajs i skärten
Tuesday, March 18, 2014 at 4:43pm

Physics
work is the product of force and the distance moved in the direction of the force. No motion = no work
Tuesday, March 18, 2014 at 3:58pm

Physics
6987
Tuesday, March 18, 2014 at 3:46pm

physics
minimal, or nominal? Sine I = P/E, what's 100/120 ?
Tuesday, March 18, 2014 at 1:51pm

physics
A 5.0-nC charge is at (0, 0) and a -2.0-nC charge is at (3.0 m, 0). If the potential is taken to be zero at infinity, what is the electric potential energy of a 1.0-nC charge at point (0, 4.0 m)? Answer 1.5 × 10-8 J 3.6 × 10-9 J 1.1 × 10-8 J 7.7 × 10-9 J
Tuesday, March 18, 2014 at 1:39pm

Physics
No work = force * distance since distance=0, no work.
Tuesday, March 18, 2014 at 1:18pm

physics
What is the minimal resistance of a 100 W light bulb designed to be used in a 120 V circuit? Answer 12.0 Ω 144 Ω 1.2 Ω 0.83 Ω
Tuesday, March 18, 2014 at 1:13pm

Physics
asrh
Tuesday, March 18, 2014 at 12:48pm

PHYSICS
281m/s
Tuesday, March 18, 2014 at 12:02pm

physics
A 3.0-kg object moving 8.0 m/s in the positive x direction has a one-dimensional elastic collision with an object (mass = M) initially at rest. After the collision the object of unknown mass has a velocity of 6.0 m/s in the positive x direction. What is M?
Tuesday, March 18, 2014 at 11:01am

Physics
If you try to lift a 2 x 10 plank by applying 25 N force but plank does not move did you do any work?
Tuesday, March 18, 2014 at 10:42am

Physics
How would i solve this? (30)(Cm)Δ+(335.5)(4.18)Δ(21)=0​
Tuesday, March 18, 2014 at 8:54am

physics
Hmmm. The way I see it, kinetic energy is lost during her rise up the ramp. So, at the moment of takeoff, her KE is 1/2 mv^2 - 1/2 mgh = m(1/2 * 7.59^2 - 1/2 * 9.8 * 0.741) = 25.17m Now, that means that her speed is then 7.10 m/s The vertical component of that is 5.81 m/s, so ...
Tuesday, March 18, 2014 at 6:47am

physics
Initial momentum = 2(200) -9(20) = 400 - 180 = 220 final momentum = 11 v Conservation of momentum, Newton's First Law ---> 220 = 11 v so v = 20 m/s
Tuesday, March 18, 2014 at 4:06am

physics
A bullet A of mass 2kg travelling at 200m/s emblezes itself in a wooden block of mass 9kg moving in the opposite direction. At 20m/s. Calculate the velocity of the block when the bullet comes to rest inside the block. And what principle is used in the direction
Tuesday, March 18, 2014 at 3:59am

physics
M is irrelevant at acceleration a, v = a T L = (1/2) a T^2 a = 2 L/T^2
Tuesday, March 18, 2014 at 3:44am

physics
A skateboard with mass M rolls down a ramp, starting from rest. It takes time T to roll a distance L along the ramp. In terms of M, T, and L, what is the skateboard’s acceleration down the ramp?
Tuesday, March 18, 2014 at 1:00am

physics
The drawing shows a skateboarder moving at 7.59 m/s along a horizontal section of a track that is slanted upward by 55.0 ° above the horizontal at its end, which is 0.741 m above the ground. When she leaves the track, she follows the characteristic path of projectile ...
Monday, March 17, 2014 at 10:50pm

physics
It's not D.
Monday, March 17, 2014 at 10:43pm

Physics
A truck with 0.100 m radius tires travels at 24.0 m/s. At how many radians per second are the tires rotating? What is this in rpm?
Monday, March 17, 2014 at 10:10pm

Physics
An automobile with 0.310 m radius tires travels 85,000 km before wearing them out. How many revolutions do the tires make, neglecting any backing up and any change in radius due to wear?
Monday, March 17, 2014 at 10:10pm

Physics
In lacrosse, a ball is thrown from a net on the end of a stick by rotating the stick and forearm about the elbow. If the angular velocity of the ball about the elbow joint is 30.0 rad/s and the ball is 1.05 m from the elbow joint, what is the velocity of the ball?
Monday, March 17, 2014 at 10:10pm

physics
Complete the following nuclear reaction: ^16,v8 O + ^4, v2 He → ________ + ^19, v10 Ne 1p 1n 2H 3H
Monday, March 17, 2014 at 9:57pm

physics
F = m*a = 60 * 2.5 = 150 N. V = Vo + a*t = 0 + 2.5*4 = 10 m/s.
Monday, March 17, 2014 at 9:55pm

Physics
V = Vo + a*t = 0 + 0.3*30 = 9 m/s. d = (V^2-Vo^2)/2a = (9^2-0)/0.6 = 135 m.
Monday, March 17, 2014 at 9:39pm

Physics
A basketball player is running at 5.00 m/s directly toward the basket when he jumps into the air to dunk the ball. He maintains his horizontal velocity. (a) What vertical velocity does he need to rise 0.750 meters above the floor? (b) How far from the basket (measured in the ...
Monday, March 17, 2014 at 9:18pm

Physics
An archer shoots an arrow at a 78.0 m distant target, the bull's-eye of which is at same height as the release height of the arrow. (a) At what angle must the arrow be released to hit the bull's-eye if its initial speed is 34.0 m/s? (Although neglected here, the ...
Monday, March 17, 2014 at 9:17pm

Physics
17
Monday, March 17, 2014 at 8:55pm

PHYSICS
You throw a 20-N rock vertically into the air from ground level. You observe that when it is a height 14.8m above the ground, it is traveling at a speed of 25.0m/s upward. A) Use the work-energy theorem to find its speed just as it left the ground. What is it? B) Use the work-...
Monday, March 17, 2014 at 8:41pm

language arts -
Need to confirm if the verbs in the sentences are physical or mental actions: 1. Other Americans in the Olympics challenged their opponents, too. --physics 2. Wilma dazzled the crowds in the track & field competition. --physical 3. Al Oerter, an American discus thrower, ...
Monday, March 17, 2014 at 8:25pm

Physics
A hammer of mass M is moving at speed v0 when it strikes a nail of negligible mass that is stuck in a wooden block. The hammer is observed to drive the nail a distance L deeper into the block. A) Find the magnitude F of the force that the wooden block exerts on the nail, ...
Monday, March 17, 2014 at 8:19pm

Physics
(30)(Cm)Δ+(335.5)(4.18)Δ(21)=0​ I need to find the specific heat of the masses, but i don't know how to, i'm currently doing a lab and these are the mass and temp. numbers that i plugged in...
Monday, March 17, 2014 at 8:17pm

Physics
You throw a 20-N rock vertically into the air from ground level. You observe that when it is a height 14.8m above the ground, it is traveling at a speed of 25.0m/s upward. A) Use the work-energy theorem to find its speed just as it left the ground. What is it? B) Use the work-...
Monday, March 17, 2014 at 8:03pm

Physics
work to lift = m g h = 750 * 9.81 * 13.2 Joules/minute work for Ke = (1/2)(750)(17.4)^2 Joules/minute C) add those and divide by 60 to get Joules/second or Watts
Monday, March 17, 2014 at 7:30pm

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