Homework Definition and 998 Threads

Here is the question: A spring is compressed 20cm. When it is released, it exerts an average force of 57.2 N on a 7.3 kg rock, shooting it across a frictionless floor. Determine the speed of the rock as it leaves the spring. Homework Equations W=change in energy Work energy theorem W=Fd The...

Homework Statement Hi Guys, I am trying to solve this question, please look at the attached picture Homework Equations The general equation for a inverting amp is -Rf/R1 * Vin = Vout The Attempt at a Solution Well as the question says the two resistors, R2 and R must be treated as parallel...

Homework Statement I have a problem where a guy runs 28.5m in 11.5s, waits 45s, then runs back to the starting point in 22s. What's the average velocity? Homework EquationsThe Attempt at a Solution Would it be zero because the displacement is zero or would I calculate the 57 total meters ran...

I know the question is simple... but I don't get it. A metal ball is thrown from a tall building V0= 0. When will it reach V=25 m/s? This is my first question, I seem to like physics yet I don't understand anything... accept electricity, but the rest, I don't. I hope I don't annoy anoyone but...

So I have a physics midterm tomorrow that will have a five part, 10 point question about the following "an object pushed across a horizontal surface. You should be able to calculate net force, frictional forces from the coefficient of friction, acceleration, velocity, momentum, impulse, and...

Homework Statement Let C be the closed, piecewise smooth curve formed by traveling in straight lines between the points (-2,1), (-2,-3), (1,-1), (1,5) and back to (-2,1), in that order. Use Green's Theorem to evaluate the integral ∫(2xy)dx+(xy2)dy. Homework Equations Green's Theorem: ∫Pdx+Qdy...

Homework Statement Students are given some resistors, a battery with internal resistance, and an ammeter. They are asked to determine the emf e and internal resistance of the battery using just this equipment. Working with the circuit shown at right, they insert each resistor into the circuit...

i have recently made a hollow prism for my science exhibition in my school ... to find refractive indices of fluids. i made it using 3 rectangular pieces of glass (0.5cm) on a glass triangular base ..with obviously a hollow part in the middle it worked perfectly fine with water i got n=1.33...

Homework Statement A UPS delivery man pushes a 5kg box (A) along a smooth surface where the coefficient of kinetic friction, [µ][/k], is equal to 0.20. The box slides for 1.5m before colliding with a 3kg box (B). The boxes then move together as one unit on a rough surface with [µ][/k]= 0.9 for...

Found this on the interweb and thought it was interesting

Homework Statement In order to stop a car in shortest distance on a horizontal road, one should, (a) Apply brakes very hard so that the wheels stop rotating (b) Apply the brakes hard enough to just prevent slipping (c) Pump the brakes (press and release) (d) Shut the engine off and not apply...

Homework Statement Attached Image Homework Equations this is not a simple plane curve or a close plane curve so I use the formula: ∫ F ⋅ dr/dt dt The Attempt at a Solution From the point (0,0) to (2,4) Direction Vector v(t) = <2-0, 4-0> Parametric Equation: r(t) = (2t + 0) i + (4t + 0) j...

Hello, I am doing my special relativity homework and since the ideas are quite counter-intuitive it's hard to know if I'm doing the right things. So i'd like to post some work here and see if it is correct. Also, I am stuck on the final part of the question. 1. Homework Statement A space...

Problem Statement Two identical spheres of radius r are placed inside a cylinder of radius R as shown in the diagram below. You are given that R/2 < r < R and that each ball has a weight W. All surfaces are smooth. Show that there is a minimum mass, m, of the cylinder which will allow it to...

Hey all! I just found out and joined the forum. I am a Biomedical Engineering student and in desperate need of help. We were given couple of questions to hand in next week. I managed to solve most of them, but I'm kinda lost at these 3 questions. For question 2.1, I managed to calculate the...

Homework Statement An object whose moment of inertia is 3.00kgm2experiences the torque shown in the figure (Figure 1) . What is the object's angular velocity at 2.80s ? Assume it starts from rest. http://session.masteringphysics.com/problemAsset/1073771/4/knight_Figure_13_21.jpg Homework...

Homework Statement A worker lifts a 20.0-kg bucket of concrete from the ground up to the top of a 20.0-m-tall building. The bucket is initially at rest, but is traveling at 4.0 m/s when it reaches the top of the building. What is the minimum amount of work that the worker did in lifting the...

Homework Statement I've been told to calculate the age of the Universe at T = 1 \, \text{MeV}, assuming that a(t=0)=0. Homework Equations Now, I've already calculated the value of H at that temperature, which was around H(1\,\text{MeV}) \approx 0.6 \,\text{s}^{-1}. I've also shown, that in a...

Homework Statement I've been told to calculate the energy density in the early Universe. It states that it is completely dominated by neutrinos (3 species), photons, electrons, and positrons. Homework EquationsThe Attempt at a Solution Now, I've found an equation to calculate the energy...

Problem Statement: Moe Mentum and Ken Ettik are playing pool. Moe hits the cue ball, sending it towards the 6 ball at 2 m/s. It strikes the stationary 6 ball off-center, moving off at a 60 degree angle from the original direction after a perfectly elastic collision. Both balls have a mass of...

Homework Statement Three blocks in contact with each other are pushed across a rough horizontal surface by a 98 N force as shown. The acceleration of gravity is 9.8 m/s^2. ----F--->|2kg| |7.7kg| |9.2kg| u = 0.082If the coefficient of kinetic friction between each of the blocks and...

Homework Statement A(n) 0.142 kg baseball is thrown with a speed of 19.5 m/s. It is hit straight back at the pitcher with a final speed of 26.6 m/s. What is the magnitude of the impulse delivered to the ball? Answer in units of kg · m/s (part 2) Find the average force exerted by the bat...

Homework Statement Using the uploaded picture we have to have a force diagram. And we have to break angled forces into components and indicate which forces are equal with equality. All the masses are up to me (2, 3, 4, 5 kgs) Homework Equations Write an equation for the vertical forces Write...

"A clock has an hour hand that is 15.0 cm long, a minute hand that is 20.0 cm long, a secondhand that is 25.0 cm long." "The time is 3 h 27 min 49 s" "the hands are moving clockwise" "for the hour hand calculate 1. speed of the hand 2. velocity of the hand at the given time" "presume the hand...

Homework Statement Homework Equations All relevant equations are given above. The Attempt at a Solution I decided to make a substitution for x2 so that x2 = u. By doing that, I could make the k=n+1 and k=n-1 substitutions so I can keep the series in phase. I took y' and just plugged...

How many stones (mass=2kg) are needed to lift a TV (mass=12kg) on a seesaw? What is the weight of the stones? TV? Net force? I DEEPLY apologize if I posted this question in the wrong section AND if this question seems idiotic and simple. I am a student in high school and I am not experienced...

Homework Statement The problem is given in the attached file. Homework Equations Divergence theorem, flux / surface integral The Attempt at a Solution [/B] As you can see I got the question correct using Divergence theorem. But I wanted to make sure that I could arrive at the same answer...

Homework Statement A 500lb box is being pushed up a ramp which is sloped at 10 deg. The center of mass of the box is at the geometric center of the shown area. If the static coefficient of friction is 0.35 and the kinetic coefficient of friction is 0.28, what is the force P that will cause the...

Homework Statement ∞ n=3 ∑ ((-1)n (x+3)3n)/(2nlnn) Find radius of convergence, interval of convergence, values for x which series is: absolutely convergent, conditionally converge or divergence. Homework EquationsThe Attempt at a Solution I applied the Ratio Test and got |(x+3)3| lim...

Homework Statement A student holds a book at rest on the palm of her hand. She lifts the book straight up, bringing it to rest again at a higher point. 1. Is the net work done on the book positive, negative, or zero? 2. Is the change in the gravitational potential energy positive, negative...

Problem statement: A Helium filled balloon has a volume of 1 cubic meter and a mass of 0.200 kilograms. It is released and rises through the air because of its buoyancy. The buoyant force is equal to the weight of air displaced by the balloon.. This force is given by: F_b = [1.29e^(-1.21h)]g...

Homework Statement A space station shaped like a giant wheel has a radius 95.0 m and a moment of inertia of 5.03✕ 108 kg · m2. A crew of 150 lives on the rim, and the station is rotating so that the crew experiences an apparent acceleration of 1g. When 100 people move to the center of the...

< Moderator Note -- Thread moved here to Homework Help forum > One volume of CH4 is mixed with V volumes of air (78 vol.% N2,21 vol.% O2,1 vol.% Ar) at 1 atm and 25°C; then the mixture is ignited. Find the temperature of adiabatic combustion (the adiabatic flame temperature). The volume of air...

So here's my problem: The distance between two stars is constant(d = 4,3 * 1010m), and they have a common center of mass. Ms = mass of our star, ma = 0,82 * Ms and mb = 2,2 * Ms. What I'm supposed to do is calculate the period of orbit of both stars, which is the same for them both, since the...

Hi everyone. This is similar to my strcpy question previously. I tried to code but when I ran the code, a segmentation fault appears. I think this has something to do with my loop for the array but I have problems resolving it. May I have some help please? Thank you. My codes and the original...

Homework Statement During a rockslide, a 710 kg rock slides from rest down a hillside that is 500 m long and 300 m high. The coefficient of kinetic friction between the rock and the hill surface is 0.23...

Homework Statement A vertical spring is 10.0 cm long when supporting a 20.0 kg mass, and it is 12.0 cm long when supporting a 32.0 kg mass. Assume the stretch is linear with the load. a) What is the length of the spring with zero load? (0.06666667) b) How much work would be done in...

Homework Statement A 2000 kg car is driving up a 20° grade at a speed of 85 km/h. What force must be applied to the car to accelerate it up to 100 km/h in 10s? m= 2000 kg θ= 20° Vo= 85 km/hr = 23.6 m/s Vf = 100 km/hr = 27.8 m/s t = 10 s Homework Equations F = ma (Fx = max) Fx= Fcosθ Vox =...

Homework Statement I have given the statements: ##a_{n}^2 \ge x## , ##a_{n+1} \le a_{n}## , ##x > 0## and ##\inf a_{n} > 0 ##. How to prove the following: ##\lim_{n \to \infty}a_{n}=\sqrt{x}##Homework Equations ##a_{n}^2 \ge x## , ##a_{n+1} \le a_{n}## , ##x > 0## and ##\inf a_{n} > 0 ##...

If, ##f(x)=x^x##, then, f-1(x)=?

Homework Statement Please see the attached file. Homework EquationsThe Attempt at a Solution If my math is right so far, I am basically stuck as to what to do with the E(t) term. [/B]

Mod note: This post was moved from another forum section, so doesn't use the homework template. A study of the amount of time it takes a mechanic to rebuild the transmission for a 2005 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.8 hours. If 40 mechanics...

[FONT=Arial]Can someone check these for accuracy please? 1. Homework Statement 1. Light really passes through the position of a real image whether or not a screen, film, or ground glass is there to catch it. 2. You need a screen or ground glass to make a virtual image visible. 3. In a...

Homework Statement Figure 29-61 shows a cross section of a long thin ribbon of width w = 4.91 cm that is carrying a uniformly distributed total current i = 4.61 * 10^-6 A into the page. What is the magnetic field at a point in the plane of the ribbon at a distance 2.16 cm from its edge...

1. The problem statement Peter threw 10 (same) coins into an empty container (a tube/drum), which was floating in A LIQUID. The diameter of the container was 2,257 cm, and so because the container is a tube the surface of the tube was equal to π times the diameter squared. He measured, after 4...

Homework Statement While rolling balls down an inclined plane, Galileo observes that the ball rolls 1 cubit (the distance from elbow to fingertip) as he counts to 10. How far will the ball have rolled from its starting point when he has counted to 20? The answer I get is supposed to be 4...

Homework Statement A 34.05 gram liquid sample of an unstable compound is deposited in a metal piston assembly that has a cylinder with a diameter of 20.0 cm. After the sample is added, the piston is placed in contact with the liquid and the piston vent is closed. This process removes all...

Homework Statement 4 charges of +5µC, +3µC, -4µC and +2µC form the 4 points of a square of side length 2m. Calculate the field strength and potential at the centre of the square. Homework Equations F=1/4πhttp://upload.wikimedia.org/math/d/3/c/d3c305fc416b971cd6d284564e51bf85.png0 X Q1Q2/r2 E=...

It isn't until recently that I have really taken to heart the idea of really understanding and doing homework problems. I feel like I'm learning at a much more controlled pace if I work along with problems in a book (example: solving them before reading the solution), but aside from this, is...

Problem Show: \int_0^\infty \frac{cos(mx)}{4x^4+5x^2+1} dx= \frac{\pi}{6}(2e^{(-m/2)}-e^{-m}) for m>0 The attempt at a solution The general idea seems to be to replace cos(mx) with ##e^{imz}## and then use contour integration and residue theory to solve the integral. Let ##f(z) =...