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April 16, 2014

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Recent Homework Questions About Physics

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physics
.24 g answered in another of your questions
Friday, February 21, 2014 at 1:39pm

physics
weight - 126 g friction force = 126 * 9.81 * .7 = F if no acceleration
Friday, February 21, 2014 at 1:38pm

physics
d = (1/2) a t^2 solve for a F = m a = mu m g so mu = a/g
Friday, February 21, 2014 at 1:37pm

physics
loss of potential energy = m g h gain of kinetic energy = (1/2)m v^2 difference = work against friction which = F * 53 neters
Friday, February 21, 2014 at 1:35pm

physics
A -kg block is initially at rest on a frictionless horizontal surface. It is pulled with a constant horizontal force N. How long must it be pulled before its speed is m/s? t_{pull} =
Friday, February 21, 2014 at 1:17pm

physics
A block with a mass of 126 kg is pulled with a horizontal fource of F_{applied} across a rough floor. The coefficent of friction between the floor and the block is 0.7. If the block is moving at a constant velocity, what is the magnitude of F_{applied}? F_{applied} =
Friday, February 21, 2014 at 1:16pm

physics
A 7 kg purse is dropped from the top of the Leaning Tower of Pisa and falls 53 m before reaching the ground with a speed of 17 m/s. What was the average force of air resistance? F_{average} =
Friday, February 21, 2014 at 1:15pm

physics
Drag-race tires in contact with an asphalt surface have a very high coefficient of static fric.tion. Assuming a constant acceleration and no slipping of tires, estimate the coefficient of static friction needed for a drag racer to cover 2.1 km in 8 s, starting from rest. ...
Friday, February 21, 2014 at 1:14pm

physics
What is the maximum acceleration a car can undergo if the coefficient of static friction between the tires and the ground is 0.24? a_{max} =
Friday, February 21, 2014 at 1:14pm

physics
A force of 48 N is required to start a 7.8 kg box moving across a horizontal concrete floor. (a) What is the coefficient of static friction between the box and the floor? \mu_s = (b) Does the coefficent of friction have a unit? A. No, it is a ratio B. No, the units are not ...
Friday, February 21, 2014 at 1:13pm

physics
Three blocks on a frictionless horizontal surface are in contact with each other. A force F is applied to block A and the blocks start to slide to the right of their initial position. Determine the acceleration of the system, if m_A = 12 kg, m_B = 38 kg, m_C = 4700 g, and F = ...
Friday, February 21, 2014 at 1:12pm

Physics
A single mass (m1 = 3.2 kg) hangs from a spring in a motionless elevator. The spring constant is k = 253 N/m. 1) What is the distance the spring is stretched from its unstretched length? This first answer is equal to 12.4 cm but I am having trouble on the second question... 2)...
Friday, February 21, 2014 at 12:04pm

physics
zero because F = m a = m*0.00
Friday, February 21, 2014 at 11:14am

physics
If a toy plane is spinning on a string 1.87 meters off the ground and the string is .5m long how long does it take to make 10 revolutions?
Friday, February 21, 2014 at 11:04am

physics
(a) A car with a mass of 950 kg is moving to the right with a constant speed of 1.45 m/s. What is the total force on the car? (b) What is the total force on the car if it is moving to the left?
Friday, February 21, 2014 at 10:58am

physics
A block weighing 71.5 N rests on a plane inclined at 24.1° to the horizontal. The coefficient of the static and kinetic frictions are 0.26 and 0.13 respectively. What is the minimum magnitude of the force F, parallel to the plane, that will prevent the block from slipping?
Friday, February 21, 2014 at 9:59am

Physics
An airplane with an airspeed of 50km/h lands on a runway where the wind speed is 30km/h .
Friday, February 21, 2014 at 9:53am

physics
bff
Friday, February 21, 2014 at 9:25am

Physics
A train moving at a constant speed on a surface inclined upward at 10.0° with the horizontal travels a distance of 400 meters in 5 seconds. Calculate the vertical velocity component of the train during this time period
Friday, February 21, 2014 at 9:06am

Physics
At the instant a race began, a 89.1 kg sprinter exerted a force of 710 N on the starting block in the direction 110 degrees measured clockwise from the positive x-axis. (a) What was the horizontal acceleration of the sprinter? a_x = (b) If the force was exerted for 0.7 s, ...
Friday, February 21, 2014 at 2:12am

physics
A person stands on a bathroom scale on a motionless elevator. When the elevator begins to move, the scale briefly reads 200 percent of the person's regular weight. Calculate the acceleration of the elevator, a_{elevator}. Use SI units
Friday, February 21, 2014 at 2:07am

physics
Two spheres are launched horizontally from a 0.8 m high table. Sphere A is launched with an initial speed of 16 m/s. Sphere B is launched with an initial speed of 8 m/s.
Thursday, February 20, 2014 at 11:26pm

Physics
A rifle shoots a 4.1g bullet out of it's barrel. The bullet has a muzzle velocity of 975 m/s just as it leaves the barrel. Assuming a constant horizontal acceleration over a distance of 43.0 cm starting from rest, with no friction between the bullet and the barrel, what ...
Thursday, February 20, 2014 at 10:20pm

Physics
a. Tan A = Y/X = -100/38 = -2.63158 A = -69.2o = 69.2o S of E=20.8o E of S. The bird must head 20.8o W of S. b. d = V*t = 600 km 100t = 600 t = 6 h.
Thursday, February 20, 2014 at 10:11pm

physics
A 475 gram box is given a push and it then slides up and back down a ramp with a 35.0° incline. The coefficient of friction is 0.30. (a) Determine the rate of deceleration as the box slides up the ramp. (b) Determine the rate of acceleration as the box slides back down ...
Thursday, February 20, 2014 at 9:45pm

Physics
A. F = F1 + F2 = 81N[80o] + 90N[22o] F=(81*cos80+90*cos22)+(81*sin80+90*sin 22)i = 97.51 + 113.5i F = sqrt(97.51^+113.5^2) = 149.6 N. B. Tan A = Y/X = 113.5/97.51 = 1.16398 A = 49.3o = Direction.
Thursday, February 20, 2014 at 9:34pm

physics
dasd
Thursday, February 20, 2014 at 9:28pm

physics
V^2 = Vo^2 + 2a*d a = (V*2-Vo^2)/2d a = (0.59^2-0)/0.86 = 0.405 m/s^2. Fn = m*a = 72 * 0.405 = 29.1 N.
Thursday, February 20, 2014 at 9:01pm

physics
Y^2 = Yo^2 + 2g*h = 0 Yo^2 - 19.6*0.291 = 0 Yo^2 = 5.70 Yo = 2.39 m/s = Ver. component of initial velocity. Vo = Yo/sin A = 2.39/sin3.42 = 40.0 m/s. [3.42o]
Thursday, February 20, 2014 at 8:45pm

physics
Suppose two children push horizontally, but in exactly opposite directions, on a third child in a wagon. The first child exerts a force of 75.0 N, the second a force of 95.0 N, friction is 12.0 N, and the mass of the third child plus wagon is 21.0 kg. (c) Calculate the ...
Thursday, February 20, 2014 at 8:33pm

Physics
a 2.5 kg ball moving at 7.50 m/s is caught by a 70.0 kg man while the man is standing on ice. how fast will the man / ball combination be moving after the ball is caught by the man?
Thursday, February 20, 2014 at 8:16pm

Physics
Dx = Xo * Tf = 0.315 m. 0.582 * Tf = 0.315 Tf = 0.541 s. = Fall time or time in air Y = Yo + g*t = 0 + 9.8*0.541 = 5.30 m/s. = Ver. component of final velocity.
Thursday, February 20, 2014 at 7:28pm

physics
The orbital period of Io, one of Jupiter,s moons, is 1.77 days ( 1.53 x 10 to the 5 power). If Io orbits Jupiter at a radius of 4.22 x 10 to the 8 power meters, what is the mass of Jupiter?
Thursday, February 20, 2014 at 6:38pm

physics
A 33.3- kg block (m1) is on a horizontal surface, connected to a 5.1- kg block (m2) by a massless string. The pulley is massless and frictionless. A force of 220.1 N acts on m1 at an angle of 32.p deg. The coefficient of kinetic friction between m1 and the surface is 0.201. ...
Thursday, February 20, 2014 at 5:10pm

physics
A 33.3- kg block (m1) is on a horizontal surface, connected to a 5.1- $kg$ block (m2) by a massless string. The pulley is massless and frictionless. A force of 220.1 N acts on m1 at an angle of 32.p deg. The coefficient of kinetic friction between m1 and the surface is 0.201. ...
Thursday, February 20, 2014 at 5:09pm

Physics
What would be the answers to A and B?
Thursday, February 20, 2014 at 5:09pm

physics
A block weighing 71.5 N rests on a plane inclined at 24.1° to the horizontal. The coefficient of the static and kinetic frictions are 0.26 and 0.13 respectively. What is the minimum magnitude of the force F, parallel to the plane, that will prevent the block from slipping?
Thursday, February 20, 2014 at 5:05pm

Physics
60 = (1/2)(3.37) t^2 solve fot t, the rolling time v = a t = 3.37 t that v is the speed at the cliff edge u = v cos 21 = horizontal speed until bottom Vi = -v sin 21 = initial speed up (negative of course) h = Hi + Vi t + (1/2) a t^2 now t is the time airborne 0 = 30 - v (sin ...
Thursday, February 20, 2014 at 4:41pm

Physics
A car is parked on a cliff overlooking the ocean on an incline that makes an angle of 21.0° below the horizontal. The negligent driver leaves the car in neutral, and the emergency brakes are defective. The car rolls from rest down the incline with a constant acceleration ...
Thursday, February 20, 2014 at 4:32pm

physics
F = m a G M m/R^2 = m v^2/R but T = 2 pi R/v time for circumference rounding so v^2 = (2 pi R/T)^2 = (2 pi)^2 R^2/T^2 so G M/R^2 = (2 pi)^2 R/T^2 G M/(2pi)^2 = R^3/T^2 ( but Kepler knew that :) = Rnew^3/Tnew^2 = (2R)^3/Tnew^2 = 8 R^3/Tnew^2 so Tnew^2 = 8 T^2 Tnew = 2 sqrt 2 T ...
Thursday, February 20, 2014 at 4:15pm

physics
the distance from the earth to the sun is 1.5 times 10 to the 11 power m ( 93 million miles) and the time for one complete orbit of the earth about the sun is one year. how long would it take a planet located at twice this distance from the sun to complete one orbit?
Thursday, February 20, 2014 at 3:54pm

Physics
I can only help with A, but use the equation h=(V^2*sin^2(angle))/(2*g) For your particular question I got, 4.306 meters.
Thursday, February 20, 2014 at 3:11pm

Physics
78
Thursday, February 20, 2014 at 2:44pm

Physics
A ball is thrown upward in two dimensions with an initial speed of 17 Zlugs per mega handle(made up) near the surface of the planet earth. What will be the y component of the balls velocity at the peak of its trajectory?
Thursday, February 20, 2014 at 2:07pm

Physics
A 439g block is placed on a spring with a spring constant of 193N/m, compressing it 28cm. What height does the block reach when it is launched?
Thursday, February 20, 2014 at 12:29pm

physics
choose the correct answer and why? a car starts from rest and reaches speed of 80 km/h in 16 s the average acceleration of the car is: a\ 0.7 m/s*2 b\1.4 m/s*2 c\5 m/s*2
Thursday, February 20, 2014 at 12:27pm

Physics
A 14g bullet is traveling at 306m/s when it strikes a block of wood. If the block of wood exerts a force of 50,000 N opposing the motion of the bullet, how far will the bullet penetrate the block of wood?
Thursday, February 20, 2014 at 12:24pm

Physics
A uniform rope with length L and mass m is held at one end and whirled in a horizontal circle with angular velocity w. You can ignore the force of gravity on the rope. (a) At a point on the rope a distance r from the end that is held, what is the tension F? (b) What is the ...
Thursday, February 20, 2014 at 12:22pm

physics
to clear any confusion, the cart rolls down a hill
Thursday, February 20, 2014 at 12:20pm

physics
If the cart weighs 8.7kg and the cart starts at a height of 3m, what is the final velocity of the cart? the starting velocity is 0
Thursday, February 20, 2014 at 12:15pm

Physics
Inward force needed =m a = m v^2/R = 600 (900)/120 = 4500 Newtons inward down slope component = 4500 cos 25 Force up slope = Ff friction weight down slope = m g sin 25 = 2488 Net force down slope = 2488 - Ff so 2488-Ff = 4500 cos 25 Ff = 2488 - 4078 Ff = -1590 N so 1590 DOWN ...
Thursday, February 20, 2014 at 11:30am

Physics
10
Thursday, February 20, 2014 at 10:44am

Physics
diameter does not matter p = density * g * depth (the weight of water in a 1 m^2 column) so water weighs 1000 kg/m*3 so we are talking a mass of 1000 * 20 20,000 * 9.81 = 196,200 or 1.96*10^5 Newtons/m^2 or Pascals HOWEVER on to of that you have the air pressure which is about...
Thursday, February 20, 2014 at 10:42am

physics
10.5m
Thursday, February 20, 2014 at 10:01am

Physics
A 600-kg car is going around a curve with a radius of 120 m that is banked at an angle of 25.0° with a speed of 30.0 m/s.The coefficient of static friction between the car and the road is 0.300. What is the force exerted by friction on the car?
Thursday, February 20, 2014 at 6:22am

Physics
mass of system = M = .082 + 863 Kinetic energy at bottom = potential energy at top (1/2) M v^2 = M g (.045) or v^2 = 2 (9.8)(.045) solve for v, total velocity at bottom after collision note - the masses do not matter
Thursday, February 20, 2014 at 5:42am

Physics
train goes 27 t meters car goes 27 t + 29 meters so 27 t + 29 = 38 t + (1/2)(2) t^2
Thursday, February 20, 2014 at 5:37am

physics 2
Power = i^2 R energy = power * time = i^2 R t in Joules t = 60 seconds set that equal to heat energy used to warm the battery type this into Google search box 0.2 kcal/kg K = Joules/kg K to get C = 836.8 J/kg K i^2 R t = 836.8 * 20kg * (delta T) solve for delta T
Thursday, February 20, 2014 at 5:34am

Physics
F = m a Would it not be easier to do the problem than to type it here?
Thursday, February 20, 2014 at 5:26am

physics 2
a certain 12v storage battery with an internal resistance of 12 ohms delivers 80 A when used to crank a gasoline engine. if the battery mass is 20 kg and it has average specific heat of 0.2 kcal/kg K. what is its rise in temperaure during 1 min of cranking the engine. assume ...
Thursday, February 20, 2014 at 4:44am

Physics
A train is moving parallel and adjacent to a highway with a constant speed of 27 m/s. Ini- tially a car is 29 m behind the train, traveling in the same direction as the train at 38 m/s and accelerating at 2 m/s2. What is the speed of the car just as it passes the train? Answer...
Thursday, February 20, 2014 at 2:30am

Physics
A student performs a ballistic pendulum experiment using an apparatus similar to that shown in the figure. Initially the bullet is fired at the block while the block is at rest (at its lowest swing point). After the bullet hits the block, the block rises to its highest ...
Thursday, February 20, 2014 at 2:28am

physics
A cart of mass m = 1.10 kg on a track undergoes a collision with another cart. It's velocity before and after the collision, vi and vf is measured and found to be vi = 2.12¡À0.06 m/s and vf = 0.60¡À0.08 m/s. Calculate the following quantities ...
Wednesday, February 19, 2014 at 11:52pm

Physics
A 30m high cylindrical water tank has a diameter of 14m. The tank is two-thirds full of water. What is the pressure at the bottom of the tank?
Wednesday, February 19, 2014 at 11:49pm

Physics
Find the net force and the acceleration for the situation below. 30N 20N <---------------[ 5.1kg]---------->
Wednesday, February 19, 2014 at 11:44pm

Physics
I only need help with part B. A 250W computer power supply is on 10 h per day. Part A If the cost of electricity is $0.15/kWh, what is the energy cost (to the nearest dollar) if this computer is used like this for a year (365 days)? 140 dollars Part B If this power supply is ...
Wednesday, February 19, 2014 at 11:16pm

Physics
A block of mass 21.0kg kg slides down a frictionless surface inclined at 33 ∘ ^\circ.To ensure that the block does not accelerate, what is the magnitude of the smallest force that you must exert on it?
Wednesday, February 19, 2014 at 10:56pm

Physics
6.0 joules
Wednesday, February 19, 2014 at 10:55pm

Physics
A certain radioactive element has a half liv of 20days, how long does it take 3/2 of the atom originally present to disintegrate
Wednesday, February 19, 2014 at 10:15pm

Physics
d = Vo*t + 0.5g*t^2 = 5.15 m. 0 + 4.9t^2 = 5.15 t^2 = 1.05 Tf = 1.025 s. = Fall time. Dx = Xo * Tf = 11.9 m. Xo * 1.025 = 11.9 Xo = 11.6 m/s = Required speed.
Wednesday, February 19, 2014 at 10:13pm

Physics
conservation of momentum 2-1=(2)V v=.5m/s in the direction of the original 2m/s velocity
Wednesday, February 19, 2014 at 10:10pm

physics
Vo = 35.2 Ft/s * 1m/3.3Ft = 10.7 m/s.
Wednesday, February 19, 2014 at 9:55pm

physics
Y^2 = Yo^2 + 2g*h = 0 Yo^2 - 64*11.7 = 0 Yo^2 = 748.8 Yo = 27.4 Ft/s = Ver. component of the initial velocity. Vo = Yo/sinA = 27.4/sin51 = 35.2 Ft/s = Initial velocity = Speed at which the animal must leave gnd.
Wednesday, February 19, 2014 at 9:46pm

Physics
You are general in the Napoleonic wars. You are on top of a plain 12m talk and you have a cannon tht can shoot a cannonball out at 350 m/s. 800 m away is a thick forest that you cannot see into but one of your scouts in a hot air balloon has just signaled to you that an enemy ...
Wednesday, February 19, 2014 at 9:42pm

physics ^^^^^^^^^
!@#$%^& off i want the answer
Wednesday, February 19, 2014 at 9:36pm

Physics
You are a general in the Napoleonic wars. An enemy fort 10m tall is located 1000m from your cannon. Your cannon expert is insisting that you will get the best results at an angle of 25 above the horizontal. Your cannon is located on a hill 10m tall. You have soldiers storming ...
Wednesday, February 19, 2014 at 9:36pm

physics
fuc k you
Wednesday, February 19, 2014 at 9:33pm

Physics
You are a general in the Napoleonic war. The battle has taken you to a trench 7m deep. You have a mortar that will fire an explosive at a speed of 200 m/s at an angle of 80. You have a low flying reconnaissance airplane scouting out the enemy troops at a height of 500 m. Your ...
Wednesday, February 19, 2014 at 9:31pm

Physics
Suppose you are a general in the Napoleonic wars. You are no top of a plain 50 m high overlooking the enemy soldiers. You now have a brand new cannon that will decimate the enemy. Unfortunately in the christening process you used some rather cheap grade champagne and all the ...
Wednesday, February 19, 2014 at 9:27pm

Physics
Two identical gliders slide toward each other on an air track. One moves at 2 m/s and the other at 1 m/s. If they stick together, the combination slides at? Why?
Wednesday, February 19, 2014 at 9:24pm

Physics
A ball is thrown upward in two dimensions with an initial speed of 17 Zlugs per mega handle(made up) near the surface of the planet earth. What will be the y component of the balls velocity at the peak of its trajectory?
Wednesday, February 19, 2014 at 8:58pm

Physics
A cannon shoots a cannonball with an initial speed of 25 m/s at an angle 13. 1. What is the x component of the cannonballs initial velocity Vox? 2. What is the y component of the cannonballs initial velocity Voy? 3. What will be Vy, the y component of the cannonballs final ...
Wednesday, February 19, 2014 at 8:57pm

Physics
A cannon fires a free projectile at an angle 85 from the ground. The cannonball has a speed of 150 m/s and it is launched from a hill 20 m above the plain where it will land 1. What is the x component of the cannonballs initial velocity 2. What is the y component of the ...
Wednesday, February 19, 2014 at 8:56pm

Physics
1a. 2.5m[30o] X = 2.5*cos30 = 2.17 m. Y = 2.5*sin30 = 1.25 m. P1(2.17,1.25). 3.8m[120o] X = 3.8*cos120 = -1.9 m. Y = 3.8*sin120 = 3.29 m. P2(-1.9,3.29). 1b. (2.17,1.25), (-1.9,3.29) d^2=(-1.9-2.17)^2 + (3.29-1.25)^2= 20.73 d = 4.55 m. 2. A + B = -14 29i + B = -14 B = -14 -29i...
Wednesday, February 19, 2014 at 8:49pm

Physics
A. Consider the motion of a projectile. It is fired at t= 0. Its initial speed is 12 m/s and its initial projection angle is 50◦ from the horizontal. The acceleration of gravity is 9.8 m/s^2. What is the maximum height,h, of its trajectory? Answer in units of m. B. ...
Wednesday, February 19, 2014 at 8:48pm

Physics
A small rocket weighs 14.7 newtons. The rocket is fired from a high platform but it's engine fails to burn properly. The rocket gains total upward force if only 10.2 newtons. At what rate and in what direction is the rocket accelerated?
Wednesday, February 19, 2014 at 8:41pm

Physics
During a baseball game, a batter hits a pop-up to a fielder 78 m away. The acceleration of gravity is 9.8 m/s^2. If the ball remains in the air for 5.7 s, how high does it rise? Answer in units of m.
Wednesday, February 19, 2014 at 8:37pm

Physics
123
Wednesday, February 19, 2014 at 8:28pm

Physics 101
Consider two waterfalls, one twice the height of the other. The kinetic energy of each kilogram of water falling to the bottom of the taller waterfall is about?
Wednesday, February 19, 2014 at 8:08pm

physics
A 400 g marble block has a specific heat of 860 J/kg C deg. If the block is placed in 700 ml of water, the marble changes it temperature by 17 Celsius degrees. Since the specific heat of water is known to be 4186 J/kg C deg, what is the temperature change of the water. (The ...
Wednesday, February 19, 2014 at 7:20pm

physics
A wave travels at 575 m/sec in a dense media. The wave is observed to The length of the media is 95.8 cm. When the wave is reflected at the end, its phase is reversed (an upward motion becomes a downward motion.) What is the frequency of the resonant wave in this media?
Wednesday, February 19, 2014 at 7:19pm

physics
The speed of sound in air varies with the temperature and humidity of the air. In dry air at 20 degrees Celsius, the speed of sound is approximately 343 m/sec. A closed tube resonates with a node at each end for a sound wave in air. What is the length of tube you would choose ...
Wednesday, February 19, 2014 at 7:19pm

Physics
b
Wednesday, February 19, 2014 at 6:54pm

Physics
The distance from the earth to the sun is 1.5 times 10 to the 11 power m ( 93 million miles) and the time it takes for one complete orbit of the earth about the sun is one year. How long would it take for a planet located at twice this distance from the sun to complete one orbit?
Wednesday, February 19, 2014 at 6:53pm

Physics
normal component of weight = 45*9.81* cos 41 so friction force = 0.45* 45*9.81*cos 41 component of weight down slope = 45*9.81 * sin 41 so 45 a = 45*9.81*sin 41 - .45*45*9.81*cos 41 or a = 9.81* (sin 41 - .45 cos 41)
Wednesday, February 19, 2014 at 6:40pm

Physics
A 45kg block slides down an incline that is angled at 41 degrees. If the coefficient of kinetic friction between the block and the incline is 0.45 what is the block's acceleration?
Wednesday, February 19, 2014 at 5:59pm

PHYSICS
v = her speed c = current speed (v+c) * 2 = 10 (v-c) * 3 = 10 v + c = 5 = 15/3 v - c = 10/3 --------------subtract 2 c = 5/3 c = 5/6
Wednesday, February 19, 2014 at 3:46pm

PHYSICS
A girl rows 10 km downstream in 2 h. Her return trip takes 3 h. How fast is the current. in km/
Wednesday, February 19, 2014 at 3:36pm

PHYSICS
G-Good job N-Naruto-kun
Wednesday, February 19, 2014 at 3:31pm

PHYSICS
average speed during constant acceleration = (end speed+start speed)/2 = (0 + 28.8)/2 = -14.4 m/s Now if you want the average force for the next part of the qustion F = d momentum/ d time = - mass of driver (28.8) /(.93/-14.4)
Wednesday, February 19, 2014 at 3:27pm

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