Net force Definition and 504 Threads

Net force is the vector sum of forces acting on a particle or body. The net force is a single force that replaces the effect of the original forces on the particle's motion. It gives the particle the same acceleration as all those actual forces together as described by Newton's second law of motion.
In physics, it is possible to determine the torque associated with the point of application of a net force so that it maintains the movement of jets of the object under the original system of forces. Its associated torque, the net force, becomes the resultant force and has the same effect on the rotational motion of the object as all actual forces taken together. It is possible for a system of forces to define a torque-free resultant force. In this case, the net force, when applied at the proper line of action, has the same effect on the body as all of the forces at their points of application. It is not always possible to find a torque-free resultant force.

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  1. R

    What Does Fd Represent in Net Force Calculations?

    I'm trying to calculate the acceleration of an object but first I need to calculate the net force. For this question we were told Fnet = Fa-Fd-Ff.. just wondering what Fd is? Thank you in advance.
  2. V

    Net Force and Applied Force: Calculating Acceleration and Friction Coefficients

    Homework Statement 1.) An 11 kg block is being pushed forward on a flat surface with a force of magnitude 45 N. The coefficient of kinetic friction is 0.12 and the coefficient of static friction is 0.15. What is the accleration of the object, and what is the net force acting on the object...
  3. S

    Net force = 0, but potential increases?

    G'day, Just wondering if someone can explain to me how when an object is moved to a higher point above the earth, if initial velocity = final velocity, the net work done is zero? The way I see it the object now has a greater gravitational poitential energy and although no kinetic energy is...
  4. P

    How Much Force Is Needed for a 450g Object to Accelerate at 8cm/s²?

    ' a mass of 450 grams is given an acceleration of 8cm/s/s. Calculate the net force required. so confused, the only question i couldn't get was this one.
  5. B

    Where on the x-axis will a third charge have no net force

    Homework Statement Where on the x-axis would the net force on a (-2) micro Coulomb charge be zero? *picture attached* Homework Equations F = k*(q1q2)/d^2 The Attempt at a Solution I think the answer is d= 6, making the position on the x-axis = 7. However, when solving my equation, I have...
  6. jegues

    How to Calculate Net Magnetic Force on a Current Loop?

    Homework Statement See figure attached. Homework Equations The Attempt at a Solution I'm confused as how to calculate the net magnetic force that acts on the loop. Do I choose a point somewhere and calculate the magnetic force with respect to that? Because I don't quite...
  7. T

    Weight, net force, and acceleration

    Homework Statement A parachutist relies on air resistance (mainly on her parachute) to decrease her downward velocity. She and her parachute have a mass of 55.0 kg and air resistance exerts a total upward force of 620 N on her and her parachute. A.) What is the weight of the parachutist? B.)...
  8. M

    How Do I Calculate the Net Force on Sphere A in This Coulomb's Law Problem?

    I don't really know how to solve this problem. I only know how to calculate the net force on B, not A... here is the problem: sphere A is located at the origin and has a charge of +2.0x10^-6 C. Sphere B is located at +.6m on the x-axis and has a charge of -3.6x10^-6 C. Sphere C is located...
  9. F

    How Do You Calculate the Net Force on a Charge in an Electric Field?

    Homework Statement A point charge +2Q is at the origin and a point charge -Q is located along the x-axis at x=d. Find a symbolic expression for the net force on a third point charge +Q located along the y-axis at y = d Answer = k\frac{Q^2}{d^2}<\frac{1}{2\sqrt{2}}, 2 -...
  10. C

    Finding the net force on a charge in the center of 4 other charges.

    Homework Statement Four charges Aq,Bq,Cq, and Dq (q = 5.00 × 10-7C) sit in a plane at the corners of a square whose sides have length d = 83.0 cm, as shown in the diagram below. A charge, Eq, is placed at the origin at the center of the square. DATA: A = 2, B = 4, C = 7, D = 4, E = -5...
  11. F

    Net force is Zero, quadratic answers

    Homework Statement Three point charges lie along the x axis. The positive charge q1 = 15.0uC and is at x = 2.00m (2.00 away from the origin), the positive q2 = 6.00uC is at the origin. The net force on q3 which is between q2 and q1 is 0. What is the x coordinate of q3? solution My...
  12. jegues

    Placing a 3rd charge so there is no net force

    Homework Statement See figure attached for problem statement as well as the figure given. Homework Equations The Attempt at a Solution If a throw a third charge 3 into the mix the forces on each charge should be as follows: \vec{F_{1}} = \vec{F_{13}} + \vec{F_{12}}...
  13. F

    Determine the net force acting on a ball as it rolls down a ramp.

    Homework Statement I am doing a Gr. 11 Physics project and my task is:Determine the net force acting on a ball as it rolls down a ramp. m= 46.7 d(horizontal of ramp/length)= 92.5cm h (height of the ramp from floor to tallest point)= 45.0cm time for ball to roll down= 0.61s Homework...
  14. L

    Net force due to gravity (sort of conceptual questions)

    Homework Statement http://edugen.wiley.com/edugen/courses/crs4957/art/qb/qu/c13/fig13_37.gif Masses m are the same on the bottom, and the net gravitational force is 0 on m4 which is located at the center of an equilateral triangle. What is the mass of M? Homework Equations Fg=GmM/r^2...
  15. I

    Neutralizing Forces Between Electric Charges

    Homework Statement Consider a charge of +2.0 µC placed at the origin of an X-Y co-ordinate system and a charge of -4.0 µC placed 40.0 cm to the right. Where must a third charge be placed – between the charges, to the left of the origin, or beyond the second charge – to experience a net force of...
  16. H

    Net Force on 5kg Suitcase and Applied Force Calculation

    Homework Statement What is the net force acting on a 5kg suitcase when picked up with 60N of force? what is the applied force? What is the acceleration of the suitcase? Homework Equations ma=? The Attempt at a Solution I'm not even sure on how to start the equation all I know...
  17. R

    Calculate the net force of space shuttle

    Homework Statement Right after clearing the launch tower, the space shuttle is accelerating upward at 6 m/s/s. a) Calculate the net force on an 80 kg astronaut during this acceleration. b) Calculate the force that the seat must exert on the 80 kg astronaut during this acceleration. c) A...
  18. M

    Trouble finding the magnitude of a net force required.

    Here is the problem I have: 1. A 800 kg rocket sled can be accelerated at a constant rate from rest to 1500 km/h in 2.1 s. What is the magnitude of the required net force? First I converted the a from 1500 km/h to 416.7 m/s I then used F=ma but I got the result as 333360 N but this answer is...
  19. R

    Help with magnitude of net force

    Homework Statement A 1700kg car drives around a flat 220m -diameter circular track at 24m/s . Homework Equations What is the magnitude of the net force on the car? The Attempt at a Solution 1700 * (24^2)/(110^2) i got 80.92561983 round to two sig-figs so 81 and idk why
  20. T

    Find the net force (in Newtons)

    Find the net force (in Newtons) required to accelerate a 110 kg bike and rider from rest to a final velocity of 22.7 m/s in 10 seconds? since f=ma 110(22.7)=2497 do I divide that by 10 seconds??
  21. S

    Finding Net Force on a 725 Gram Block with Given Acceleration and Angle

    Homework Statement Find the magnitude of net force on the following object a 725 gram block that is accelerating at 8.10 m/s2 at an angle of 18.0 degree relative to horizontal. Homework Equations F=m*a The Attempt at a Solution I first converted the 725 grams to kilograms but then...
  22. S

    Finding the magnitude of net force

    How do you find magnitude of net force given mass, angle, and acceleration? I have a mass of 725 kg, an acceleration of 5.10 m/s squared and an angle of 14.0 degrees. The only equation I'm given is F=M*A but I don't know how to apply it when I have an angle as well.
  23. J

    Find net force, given velocity?

    Homework Statement Homework Equations The Attempt at a Solution a) Fnet=(2250cos(35)) * 2 - 1250 Fnet=+593 N [E] b) I have solved part a, but I don't understand how to approach part b.
  24. X

    Magnitude and direction of the net force vector

    Homework Statement The position r as a function of time of a 15.0 kg mass, moving in the x-y plane, is given by r(t) = (6.00t^3 x + 1.20t^4 y) meters where x and y are unit vectors. At t = 5.00 s, find the magnitude and direction of the net force vector which is causing this acceleration...
  25. D

    Find the net force with the given position vector

    [b]1.The position vector of a 3000N helicopter is given by: r=(.02 m/(s^3))(t^3)i + (2.2m/s)tj - (0.06 m/(s^2))(t^2)k Find the net force on the helicopter at t = 5s. [b]2. I really have no clue where to begin. [b]3. I started doing this: r=...
  26. D

    Finding Tension and w2: Solving for Angle Alpha

    Homework Statement Find Tension T and w2 in each cable in diagram. Diagram: http://i52.tinypic.com/8z33ub.jpg (i drew this in paint, sorry if it looks bad)Homework Equations only basic algebra is neededThe Attempt at a Solution To find T and w2 i need to find angle Alpha but i cannot seem to...
  27. R

    Finding the Net Force on q0 from +5q and –3q Charges

    Homework Statement A point charge +5q is located at the origin, and a point charge –3q is located on the x-axis at D = 0.361 m. At what location on the x-axis will a third charge, q0, experience no net force from the other two charges? Homework Equations F = k * (q1q2/r^2)...
  28. U

    Net Force: Tension problems with angles

    Homework Statement A rope forms a Y. At the end of the Y hangs a block with a W= 100N Whole the two upper ends are on the walls. (Left side) T{1} with an angle of 90 degrees (Right side) T{2} with an angle of 58 degrees Find the tension of each rope on the wall. Homework Equations No definite...
  29. I

    Find the Net Force and Acceleration Question

    Homework Statement The two forces F1 and F2 (shown in the figure) (i attached the figure hopefully I did it correctly) act on a 27.0 kg object on a frictionless tabletop. If F1=10.2N and F2= 16.0N, find the net force on the object and its acceleration for a and b Homework Equations...
  30. G

    Calculating Net Force from Charges

    If I have two different charges and I'm told to calculate net force, do I just use F=KQ1Q2/r^2 or Fnet=F1+F2... Please explain.
  31. G

    At what distance from the Earth and the moon have zero net force?

    Homework Statement At what distance from the Earth will a spacecraft traveling directly from the Earth to the Moon experience zero net force because the Earth and Moon pull with equal and opposite forces? Homework Equations GM(earth)/(R-d)^2=GM(moon)/d^2 The Attempt at a Solution...
  32. M

    Net Force on a Sled: 17.7 m/s^2 at 68.5°

    A 10 kg sled is pulled at 35 degrees east of north with 100 N. There is a force of 150 N due east. And a friction force of 50 N. What is the acceleration of the sled, and its direction? So I basically added up all the forces in the x direction, and the y direction, and used the pythagorean...
  33. B

    Magnitude and direction of the net force on charge -3Q and charge 4Q

    Homework Statement Four charges are located at the corners of a square as shown below. Calculate the magnitude and direction of the net force on charge -3Q and charge 4Q. (sorry don't have picture, but it is of a square with corners -Q, 2Q, -3Q, and 4Q clockwise). Homework...
  34. V

    What is the Net Force Acting on a Truck and Trailer System?

    Homework Statement A 1200 kg pickup truck tows a small 300 kg trailer using a relatively lightweight tow rope. The position of the trailer is given in m and time in s. *There is an animation which shows the truck pulling the trailer across X-axis. Given: x= -20; y= +1 **BTW, i don't know...
  35. J

    Child dragging box (friction, net force and work)

    Homework Statement A child drags a 20kg box across a lawn for 10m anfd along a sidewalk for 30m; the coefficient of friction is 0.25 for the first part of the trip and 0.55 for the second part. If the child always pulls horizontally, how much work does the child do on the box...
  36. N

    Calculating the Average Net Force of a 22g Bullet Fired from a Rifle

    A 22 g bullet is fired from a rifle. It takes 2.55 10^-3 s for the bullet to travel the length of the barrel, and it exits the barrel with a speed of 730 m/s. Assuming that the acceleration of the bullet is constant, find the average net force exerted on the bullet m=22g is a=0 ? since its...
  37. M

    Net Force and Motion Homework Solutions

    Homework Statement The 'net force' in the statements below is the sum of ALL forces acting on the body. True or False 1. During the collision of a car with a locomotive, the locomotive exerts an equal size force on the car as the car exerts on the locomotive. 2. If two objects have...
  38. W

    Calculating the Net Force of a Bouncing Ball

    Homework Statement a rubber ball mass of 0.08 kg bounces vertically on a concrete floor. the ball strikes the floor at 10 ms-1 and rebounds at 8 ms-1. The time in contact with the floor is 0.05 sec. Calculate the average net force acting on the ball during the contact with the floor...
  39. J

    Net Force on Outside Balls in a Charged System

    Homework Statement Three tiny charged metal balls are arranged on a straight line. The middle ball is positively charged and the two outside balls are negatively charged. The two outside balls are separated by 20 cm and the middle ball is exactly halfway in between. The absolute value of the...
  40. S

    What Is the Correct Calculation for Net Force on Charge 3 in an Electric Field?

    i keep getting this question wrong can some1 help -------------------------------------------------------------------------------- two point charges located on the x axis: one charge, q1 = -16.0 , is located at x1= -1.650m ; the second charge, q2= 38.5nC , is at the origin x=0. A 3rd...
  41. N

    Net Force on q2 from Charges q1-q4: Magnitude & Direction

    Homework Statement q1 = 4 mC at the origin q2 = 2 mC at x=1.0m y=0.0m q3 = 1 mC at x=1.0m y= 1.0m q4 = 3 mC at x=0.0m y= 1.0m What is the net force on q2? Give magnitude and direction of the force. Homework Equations E = kq/r^2 E = F/qThe Attempt at a Solution Ok after plotting the locations...
  42. L

    Net Force of an Object using position function and momentum principle

    Homework Statement A 2.80 kilogram mass is moving in a plane, with its x and y coordinates given by x = 4.50t2 - 1.15 and y = 2.90t3 + 1.95, where x and y are in meters and t is in seconds. Calculate the magnitude of the net force acting on this mass at t = 2.05 secondsHomework Equations...
  43. D

    How to Calculate Net Force Magnitude at Specific Time?

    Homework Statement A 2.60 kilogram mass is moving in a plane, with its x and y coordinates given by x = 5.40t2 - 1.30 and y = 2.75t3 + 1.80, where x and y are in meters and t is in seconds. Calculate the magnitude of the net force acting on this mass at t = 2.10 seconds.Homework Equations Our...
  44. E

    What average net force is required to stop .

    What average net force is required to stop... 1. a 1500 kg vehicle is traveling at 75km/h. what is the average net force required to stop the vehicle within a 4.0 second interval? 2. f=ma? but i don't know acceleration? 3. force = 1500x (75/4) ?
  45. C

    Energy, Grabity and Calculating Net Force of a Diver

    Homework Statement A 60.0-kg person, standing on a diving board, dives straight down into the water. Just before striking the water, her speed is 6.50 m/s. At a time of 1.75 s after entering the water, her speed is reduced to 1.10 m/s. What is the average net force (magnitude and direction)...
  46. H

    Balancing four point charges so that the net force acting on each charge is 0.

    Homework Statement Find positions of four charges in a plane (+1C, -1C, +2C, -2C) that result in an equilibrium (zero net force on each charge). Report positions as four (x,y) pairs. Homework Equations F = \frac{k_{e}q_{1}q_{2}}{r^{2}} The Attempt at a Solution I had no idea...
  47. C

    What is the Direction of the Net Force in this Loop?

    Homework Statement http://img8.imageshack.us/img8/8541/netforce.jpg Homework Equations The Attempt at a Solution The forces on the left and right sides cancel. The forces on the top and bottom segments of the loop are in opposite directions, so the magnitudes subtract. So i...
  48. V

    Finding Net Force of Charged Sphere

    Homework Statement I'm supposed to find the net force that the southern hemisphere of a uniformly charged sphere exerts on the northern hemisphere. I must express my answer in terms of the radius R and the total charge Q. Homework Equations F = QE \int E da = \frac{1}{\epsilon_{0}}Q The...
  49. D

    Calculating Net Force and Direction on Bolt A

    Homework Statement Four forces act on bolt A as shown. Determine the net force (in Newtons) and direction (in degrees upward from the x-axis) acting on the bolt. Homework Equations Law of Sines: a/sinA = b/sinB = c/sinC Law of Cosines: a^2= b^2 + c^2 - 2bccosAThe Attempt at a Solution I...
  50. K

    Work done on a block by net force

    [b]1. You drag a(n) 16.9 kg steamer trunk over a rough surface by a constant force of 177 N acting at an angle of 34◦ above the horizontal. You move the trunk over a distance of 59.3 m in a straight line, and the coefficient of kinetic friction is 0.186. The acceleration of gravity is 9.8...
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