Variable force Definition and 49 Threads

Can anyone tell me if my answer is wrong ?!

##W=-k(y\hat i+ x\hat j)d##. I am not getting the coordinate of particle correctly so that I can find the value of d. Also the force is varying.

Its Good to be Back! From Resnik, Fundamentals of physics: Consider a particle of mass m, moving along an x-axis and acted on by a net force F(x) that is directed along that axis. The work done on the particle by this force as the particle moves from position ##x_i## to position ##x_f## is given...

Is my solution correct? $$ F(t) = at + b $$$$W=\int_t F(t)dr, ~~~~~~~~~ ~~dr = v(t)dt$$$$W=\int_t F(t)\cdot v(t) dt$$ $$ f = \frac{dp}{dt}$$ therefore $$v(t) = \frac{1}{m}(at^2/2+bt)$$then $$W = \int_t \frac{at+b}{m}\cdot\left(\frac{at^2}{2}+bt\right)dt$$ $$W = \frac{1}{m}\int_t...

Don't really know what they want from me

Homework Statement The force on a particle is directed along an x axis and given by F = F0(x/x0 - 1) where x is in meters and F is in Newtons. If F0 = 1.5 N and x0 = 4.9 m, find the work done by the force in moving the particle from x = 0 to x = 2x0 m. Homework Equations F = force, w = work, x...

Homework Statement See the explanation of work done by variable forces given in my textbook. For calculation of work done by variable forces the author analyses only a small fraction of displacement "ds". And then he makes **assumption** that the force is acting on the particle at an angle...

Homework Statement A car of mass 2000kg moves along a horizontal road against a constant resistance of manitude (P)N. The total work done by the engine in increasing its speed from 4ms^-1 to 5.5ms^-1 while it moves a distance of 60m is 30000J. Find P. Homework Equations ΔEk+WP=WE The Attempt...

Hello all! I usually don't like to ask for help... But this is the first week of courses and I'm already stumped on a homework question... 1. Homework Statement So the question states: Find the work by the force F = x^i + xy^j. If the object starts from the origin (0,0), moves along the...

Homework Statement A CD case slides along a floor in the positive direction of an x-axis while an applied force Fa acts on the case. The force is directed along the x-axis and has the x component Fax = 7.0x – 2.0x^2, with x in meters and Fax in Newtons. The case starts at rest at the position x...

Homework Statement A pulley with a rotational inertia of ##10^{-3}\frac {kg} {m^2}## about its axle and a radius of ##10 cm##, is acted on by a force applied tangentially at its rim.The force magnitude varies with time as ##F=0.5t+0.3t^2## , with ##F## in Newtons and ##t## in...

Homework Statement The position of an object of mass 2 kg is changing as a function of time by the formula x(t) = 4t^3-6t. (a) find the work done by the forces acting on the particle between t=1 and t=3s. (b) What is the object's velocity when the force on it is zero? Homework Equations is...

Homework Statement A body of mass 5 kg is acted on by a force in a straight line. The magnitude of the force after t seconds is given by (2t - 3t^2) kg wt. If the body has an initial velocity of 3ms-1 in the same direction as the force, calculate its velocity after 4 seconds. Homework...

In my textbook, the formula used to evaluate the value of work done by horizontally placed spring has been evaluated by applying the rules of integration. I want to evaluate it with another simple way except calculas. I want to learn the simplest way to evaluate it in such a way that even a boy...

Homework Statement Force represented by F(t)=20+t+5t^2 [N] acts upon the rim of a disk. How much time has to pass before the disk has angular velocity of 200 revs\sec? R and I are known. Homework Equations \begin{equation*} \tau=I\alpha \end{equation*} \begin{equation*} \tau=R \times F...

Homework Statement A force F has components F sub x = axy-by^2, F sub y= -axy+bx^2 where a= 2N/m^2 & b=4N/m^2 Calculate the work done on an object of mass 4kg if it is moved on a closed path from (x,y) values of (0,1) to (4,1), to (4,3) to (0,3) and back to (0,1). all coordinates are in metres...

A 1.2 kg block is held against a spring of force constant 1.0 x 10^4 N/m, compressing it a distance of 0.15m. How fast is the block moving after it is released and the spring pushes it away?

Homework Statement Given Data: Graph, 2 kg particle.I am asked to calculate the work done from 0 to 4 meters, or some other interval. Normally I would simply multiply the FORCE of the given particle by multiplying 6m/s^2 times 2kg to create a new force vs. displacement graph, and then...

Homework Statement How to find the work done by a variable force in (two dimension) When F = ax^2 i + b y^3 j If a subject move from (x1,y1) to (x2, y2) Homework Equations F = dW/dr The Attempt at a Solution I tried to solve them separately by x-direction and y-direction, and then I added...

As the title alludes to, I am currently reading about work. One sentence has left me very confused, thought: " Only the magnitude of this variable force changes, not its direction, and the magnitude at any position does not change with time." Could someone possibly help me understand this?

Homework Statement An object is moved from 0 to 9 meters with a force varying according to the function F(x)= 50(5-square root x). What is the work done. Homework Equations The Attempt at a Solution I tried to take the integral and evaluate it from 0 to 9. I get 1350J no...

Homework Statement if a 10-N force is used to compress a spring with a spring constant of 4.0x10^2N/m, what is the resulting spring compression? Homework Equations The Attempt at a Solution

Homework Statement The force on a particle is directed along an x-axis and is given by F = F0(x/x0 - 1). Find the work done by the force in moving the particle from x = 0 to x = 2x0 Homework Equations The Attempt at a Solution It looks like the force is a recurrence relation or...

Dear All I would like to calculate work done on the system by variable force & distance at each point. Kindly let me know to the formula how to calculate work in excel sheet (because I'm having huge data) I have attached my copy of data for your reference. Kindly advice. Many...

Homework Statement That's a graph of Force in Newtons (y axis) vs displacement in meters (x axis) for an object of mass 3.0kg that is moving along the x-axis and initially starts at rest. I am being asked to find the total work done on the object as it moves from x = 0 to x = 7...

An electric elevator with a motor at the top has a cable weight 4.5 lb/ft. When the car is at the first floor, 198 ft of cable are paid out, and effectively 0 ft are out when the car is at the top floor. How much work does the motor do just lifting the cable when it takes the car from the first...

Homework Statement A pulley having a rotational inertia of 1.1 10-3 kg·m2 about its axle and a radius of 23 cm is acted on by a force, applied tangentially at its rim, that varies in time as F = 0.50t + 0.30t2, where F is in Newtons and t in seconds. If the pulley was initially at rest, find...

Homework Statement Hi. I am trying to learn some physics with MIT free resources (just out of personal interest), and this is where i got stuck: on section 14-13, in http://ocw.mit.edu/courses/physics/8-01-physics-i-fall-2003/lecture-notes/binder13.pdf" I am a little puzzled on how the...

Homework Statement There is a force that varies with the distance from the origin. Can I solve for the torque by integrating the force over the length of the object that the force acts on? Is it integral of F dr or F*r dr? Homework Equations torque=FxR The Attempt at a Solution I...

Homework Statement The solutions are: a)2,75J b)11,4J c)2,76m/s d)3,5J e)2,84m/sHomework Equations The Attempt at a Solution I'm having problemas trying to integrate to find the letter A (the work)! I just can't put the values that match with x=0 (this one I know hehehe) and x=2(this one I...

Answered. thank you

Homework Statement A force F=[(3x)\hat{}x-2\hat{}y]N acts on an object. How much work is done by this force as it move the object from the origin to the point r=(2\hat{}x+ 3\hat{}y)m?Homework Equations W=\intF*d\bar{}r The Attempt at a Solution W=[((3/2)x^2)\hat{}x-(2y)\hat{}y] * (2\hat{}x+...

Hello, i have an idea but i ran into a bit of a problem. I need two unidirectional output shafts rotating at unpredictable varying velocities (but predictable within a range) to be able to combine at one output shaft. I have come up with some ideas but they tend to be quite complicated... any...

Firstly, I'd like to announce that this is not a homework question, it is an example of a problem I thought up to illustrate what I have trouble with: Two spheres, each with a mass of 1 kg and a radius of 1 meter, lie in space. Their centers are 10 meters apart. When will they make contact...

If a vehicle is stopping its change in Kinetic energy is equal to the force times displacement or distance as it is traveling in a straight line and parallel to displacement. If the force is F(net) = kinetic + drag F(net) = umg + 1/2*A*rho*v^2 is this force constant or variable If it...

Homework Statement A particle experiences a variable force Fv = Fo * sin (cx) where x is displacement in meters. What units are the constants c and Fo in. Homework Equations The Attempt at a Solution Um ok...how the heck do i figure out what units they're in so i know my final...

Homework Statement An object is acted on by the force shown below. What is the final position of the object if its initial position is x = 0.40m and the work done on it is equal to (a) 0.21 J (b) (b) -0.19 J. Homework Equations W = F1x1 + F2(x2 - x1)The Attempt at a Solution a) W= F(x2-x1)...

A 8 kg brick moves along an x axis. Its acceleration as a function of its position is shown in Figure 7-37. What is the net work performed on the brick by the force causing the acceleration as the brick moves from x = 0 to x = 8.0 m? What I tried to do is find the area and multiply by the...

Homework Statement The only force acting on a 4.0 kg body as it moves along the x-axis varies as shown in the Figure. The velocity of the body at x = 0 is 6.6 m/s. What is the kinetic energy of the body at x = 6.9 m. Here's the chart...

Homework Statement A particle with a mass of 3kg is at rest at x = 3m, and then a force = (12 N/m)x is applied to it. What is the acceleration of the particle when it reaches x = 5m? Determine the v(t) for the particle. Homework Equations \sum F = ma The Attempt at a Solution...

"A cylindrical tank of height h is half full of water, all of which is to be pumped up over the side of the tank. If the total mass of the water is m, how much work must be done by the pump?" At first I tried this the easy way by simply assuming that I need to pump a mass m up to a height...

Homework Statement I need To find the work done by a force that varies with position like this: F(x)=2x^3 -5x^2 +10 with x at values between 0 to 10 meters. Homework Equations see above, and maybe w=fd The Attempt at a Solution I found the area underneath the curve by putting...

Question copied word for word 1. A particle of mass m moves in a straight line under the action of force F where F = ms, s being the displacement of the particle from O, a fixed point on the line. When s = -a the velocity of the particle is u. Find the velocity of the particle when s = 0...

Behold Halliday's Question and Halliday's answers: The only force acting on a 2.0 kg body as it moves along the x-axis varies as shown in Figure 7-41 (see attatchment). The velocity of the body at x = 0 is 4.0 m/s. (a) What is the kinetic energy of the body at x = 3.0 m? 12 J (b) At...

A single force acts on a 7.0 kg particle-like object in such a way that the position of the object as a function of time is given by x = 3.0t - 4.0t^2 + 1.0t^3, with x in meters and t in seconds. Find the work done on the object by the force from t = 0 to t = 3.0 s. I want to use the...

Hi, I'm taking a university extension program, so I can't talk with my professor. The Calc teacher at my high school doesn't understand the problem either. The Problem: Suppose that the gas in a circular cylinder of cross section area A is being compressed by a piston. If...

A 3kg object moving along the x-axis has a velocity of 2.40m/s as it passes through the origin. It is acted on by a single force Fx that varies with x as shown... a) find the work done by the force from x=0 to x = 2m b) what is the kinetic energy of the object at x=2m? c) what is the speed of...

I just did the following textbook problem (from my Calculus book under the chapter review from Applications of Integrals) but came up with an answer that differs from the one at back of the book: I reasoned as follows: The force I need to apply at any given time t to maintain constant...