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. W

    Net Force on Center Charge in Y-Direction in Square of Charges

    Homework Statement Four charges, Aq, Bq, Cq, and Dq (where q = 3.50 ×10−7 C), sit in a plane at the corners of a square whose sides have length d = 23.5 cm, as shown in the diagram below. A charge, Eq, is placed at the origin at the center of the square. (Note that A, B, C, D, and E are...
  2. J

    No Net Force in E & B Perpendicular Fields

    Homework Statement In a velocity selector E and B fields are perpendicular. Which of the following conditions on the direction of the particle's velocity can result in no net force assuming the E and B are nonzero? Homework Equations F = Eq + q(vxB) The Attempt at a Solution The...
  3. K

    Net Force, Thermal Energy & Air Insulation: Explained

    1. for fluids,why is the specific heat capacity at constan pressure is greater than that at constant volume 2. Can some one explain me about the use of air as an insulator in windows, they say it is coz of its low conductivity, how? 3. I've a got confusions about the word " net" that...
  4. K

    Coulomb's Law to find the net force

    Homework Statement Charge 8e-18 C is on the y-axis a distance 2 m from the origin and charge 9e-18 C is on the x-axis a distance d from the origin. The Coulomb constant is 8.98755e9 Nm^2/C^2. What is the value of d for which the x component of the force on 9e-18 C is the greatest...
  5. E

    Distance - Finding Equilibrium Point for Net Force

    Homework Statement At what distance from the Earth should an astronaut be placed so that he will feel no net force when the Earth and the Moon and he are aligned? Homework Equations Fnet=ma F=(Gm1m2)/d^2 The Attempt at a Solution I assume I'm going to do a force annalysis, I'm...
  6. D

    The net force on a moving positive charge

    The net force on a moving positive charge... Homework Statement A magnetic field has a magnitude of 1.2 x10^-3 T, and an electric field has a magnitude of 5.4 x10^3 N/C. Both fields point in the same direction. A positive 1.8 µC charge moves at a speed of 2.9x10^6 m/s in a direction that is...
  7. T

    What Determines the Net Force in a DNA Molecule?

    Net Force in a DNA molecule?? Homework Statement The two strands of the helix-shaped DNA molecule are held together by electrostatic forces as shown in Fig. 16-44. Assume that the net average charge (due to electron sharing) indicated on H and N atoms is 0.2e and on the indicated C and O...
  8. S

    Net force is required to bring the truck to a stop

    Homework Statement A 1.2*10power of 4 kg truck is traveling South as 22m/s A)what net force is required to bring the truck to a stop in 330m B)what is the cause of this net force Homework Equations Fnet=ma The Attempt at a Solution m=1.2*10power of 4 kg Fnet=ma = 1.2*10power...
  9. P

    Stable equilibrium and net force

    "stable equilibrium" Homework Statement Is there a difference b/w stable equilibrium and just equilibrium (of charged particles)? My homework problem exactly is: 2 small beads with charge +3q and +q each is fixed at opposite ends of a horizontal insulating rod. If a third charge is placed in...
  10. D

    Net Force on Paperweight: Help with Homework

    Homework Statement A decorative paperweight of mass 0.50 kg. sits on a desktop. The coefficient of friction is 0.60. a) How much force in the horizontal direction is needed to make the paperweight just move? b) What is the net force on the paperweight at the instant it begins to move...
  11. M

    Net Force of Wagon: Solving for f = ma

    Homework Statement A wagon with a weight of 300 N is accelerated across a level surface at .5 m/s2. What net force acts on the wagon? (g=9.81 m/s2) Homework Equations f=ma The Attempt at a Solution well the answer is 15 N, but I don't know how to get there. I need a little guide...
  12. C

    Calculate F(net): Net Force Acting on Cyclist at Finish Line

    "A cyclist competes in a one-lap race around a flat, circular course of radius r . Starting from rest and speeding up at a constant rate throughout the race, the cyclist covers the entire course in a time t. The mass of the bicycle (including the rider) is m. What is the magnitude of the net...
  13. A

    Impulse and Momentum (finding net force)

    A 0.500-kg ball is dropped from rest at a point 1.20 m above the floor. The ball reboundes straight upward to a height of 0.700 m. What are the magnitude and direction of the impulse of the net force applied to the ball during the collision with the floor? I have been trying to solve this...
  14. S

    Calculate the average net force acting on the bullet

    I have a physics problem and are woundering if someone can please help me!o:) Here's the problem: A bullet of mass 20 g strikes a fixed block of wood at a speed of 320 m/s. The bullet embeds itself in the block of wood, penetrating to a depth of 6.0 cm. Calculate the average net force acting...
  15. E

    What do I do to get the net force

    This is the question I am given: The largest mincemeat pie ever created had a mass of 1.020 x 10³ kg. Suppose that a pie with this mass slides down a ramp that is 18.0m long and is inclined to the ground by 10.0°. If the coefficient of kinetic friction is 0.13, what is the net work done on...
  16. A

    Finding a Net Force: Pulling on a Stubborn Mule

    Ok, last problem of the day lol.. I have found one answer to the problem already, I just need the other half. I'm confused about it though. Please help, thanks. Here Goes: Two people pull on a stubborn mule, as seen from a helicopter. The picture is like this: _V_ 0 Ok, in...
  17. B

    Calculating Average Net Force of 810-kg Car

    An 810-kg car accelerates from rest to 27m/s in a distance of 120m. What is the magnitude of the average net force acting on the car? 120m / 27m/s= 4.4 s F=ma =810kg * 4.4s = 3600 N This is not one of my choices. What did I do wrong?
  18. R

    What is the magnitude of the net force required for these two physical tasks?

    I have these two problems and I can't seem to find the right answer... 1)A person with a blackbelt in karate has a fist that has a mass of 0.43 kg. Starting from rest, this fist attains a velocity of 5.9 m/s in 0.25 s. What is the magnitude of the average net force applied to the fist to...
  19. E

    Net force on charges found to be zero

    I'm having trouble understanding some of these basic electrostatic priciples and my book isn't much help. I've put them in a true/false format. If I could get at few answers, it would really help me understand this. A positive point charge +q is placed at point p to the right of two...
  20. V

    Ideal gas pressure to net force

    So I know the volume of a hot air balloon and the temperatures of the air (ideal gas) inside the balloon and outside of it. I know the pressure of the air. And I need to find the Net force on the balloon and contents but neglecting the weight of the balloon itself. I thinkthere must be some way...
  21. R

    What net force is acting on the object along the incline?

    Problem: An object of mass 2.0kg starts from rest and slides down an inclined plane 69cm long in 0.90s. What net force is acting on the object along the incline? Now, I used what I was given and plugged it in the equation: deltaX=1/2at^2 + V0t I come up with acceleration = .0552...
  22. A

    Confused: Net Torque vs Net Force

    I'm taking a mechanics course & I'm confused regarding the difference of Net Force & Net Torque. Net Force refers to linear motion & Net Torque refers to rotational motion, correct? So, is it possible to have a system where the net force is zero, but the net torque is not zero? For example...
  23. K

    What Force Does a Tractor Exert to Tow a Trailer Up an Incline?

    A farm tractor tows a 4300-kg trailer up a 26 Degree incline at a steady speed of 3.0 m/s. What force does the tractor exert on the trailer? (Ignore Friction). I've tried using 3.0 m/s as the acceleration, because I don't have enough information to derive the acceleration from the kinematics...
  24. L

    What is the Direction of the Net Force on Earth?

    Hi all, I've been working on this problem for a long while and just can't get the answer. When the Earth, Moon, and Sun form a right triangle with the Earth located at the right angle, the Moon is approaching its third quarter. (The Earth is viewed here from above its north pole.) Find the...
  25. F

    Net Force and Angle Problem: Find Solution!

    I can't seem to figure our this problem. I went by the book and asked for someone else's help but i still can't figure this out. HELP! :confused: Four masses are positioned at the corners of a rectangle. 1.0kg-------x----------2.0kg l l l...
  26. S

    How Is the Net Force on Earth Calculated When Aligned with the Moon and Sun?

    When the Earth, Moon, and Sun form a right triangle with the Earth located at the right angle, the Moon is approaching its third quarter. (The Earth is viewed here from above its north pole.) Find the magnitude of the net force exerted on the Earth. Well I found the gravitational force of...
  27. T

    Net Force Questions: Answers & Help

    1. A 1.2 x 10^4 kg truck is traveling south at 22 m/s. a) What net force is required to bring the truck to a stop in 330 m? b) What is the cause of this net force? Answer: a) 8.0 x 10^3 N [N] 2. Each of the four wheels of a car pushes on the road with a force of 4.0 x 10^3 N [down]. The driving...
  28. K

    What is the Net Force on Charges in a Line?

    I'm having problems figuring this one out. Some guidance would be great! Thanks! Particles of charge Q1 = +75 µC, Q2 = +44 µC, and Q3 = -80 µC are placed in a line (Fig. 21-46). The center one is 0.35 m from each of the others. Calculate the net force on each charge due to the other two...
  29. A

    How Should Net Force and Friction Be Ranked for Blocks A and B?

    Consider two blocks, A and B on three surfaces. On each surface, block A is smaller than block B, and always positioned to the left (they are touching, with block B on the right). We have three situations: 1. Block A is pushed to the right on a smooth surface. 2. Block A is pushed to the...
  30. B

    How Does a Car Maintain Centripetal Force on a Banked Turn Without Friction?

    hello Suppose there is no friction between the car and the road -> if car is on a banked turn , the normal force ( which is always perpendicular to the road's surface ) is no longer vertical . The normal force now has a horizontal component , and this component can act as the centripetal...
  31. L

    What is the Acceleration of a Tennis Ball After Being Served?

    When a 58 g tennis ball is served, it accelerates from rest to a constant speed of 49 m/s. The impact with the racket gives the ball a constant acceleration over a distance of 45 cm. What is the magnitude of the net force acting on the ball? I tried using Fnet=ma, but acceleration isn't...
  32. 9

    Net force on a Merecedes convertible

    this is really into stuff and i fell really dumb that i can't figure this stuff out... What is the net force on a Merecedes convertible traveling along a straight road at a steady speed of 110 km/hr? Answer in N Where do i start? If it takes 1 N to push horizontally on your book to make...
  33. C

    Magnitude of the net force that acts on the charge

    A magnetic field has a magnitude of 1.2 10-3 T, and an electric field has a magnitude of 6.0 103 N/C. Both fields point in the same direction. A positive 1.8 µC charge moves at a speed of 2.6 106 m/s in a direction that is perpendicular to both fields. Determine the magnitude of the net force...
  34. K

    Net Force Questions: Answers to Help Solve Problems

    Hi, I was hoping someone could help me with some general net force questions that will help me answer some of my problems. For example, if a net force acts on an object, does the object's speed and/or velocity change? Furthermore, is the net force that acts on an object which remains at rest...
  35. A

    Dynamics - Finding the Net Force

    Once again, this is probably a very easy question, but I just can't get the answer I am supposed to get. The question is: A force of 2.0 N east and a force of 3.0 N 25degrees north of east act on an object. What is the net force of the object? ----- Now when I follow the system the...
  36. C

    Net force zero = velocity > zero ?

    net force zero = velocity > zero ?? can the net force on an object be zero yet the velocity not be zero? I say yes but under what conditions and must any restrictions be placed on the magnitude or direction of the velocity?
  37. U

    Gravitational net force of zero

    A 200 kg mass and a 500kg mass are separated by 0.4m. At what position can a 50kg mass be placed so as to experience a net force of zero (other than infinity)? here's what I did: I need both forces to equal each other. F_{200}=G\frac{200m}{x^2}=G\frac{500m}{y^2}=F_{500}...
  38. A

    Calculating the Net Force on a Spherical Shell Around the Sun

    I am beyond lost with the question, so any help would be greatly appreciated. Consider a solid, rigid spherical shell with a thickness of 100 m and a density of 3900 kg/m^3. The sphere is centered around the sun so that its inner surface is at a distance of 1.5×1011 m from the center of the...
  39. N

    Three forces acting on object, find net force

    Forces -------------------------------------------------------------------------------- Three forces F1, F2 and F3 act on an object as shown in the free-body diagram above. F1 has a magnitude of 6 N while F2 and F3 each have a magnitude of 3 N. All forces make angles of 30° with the...
  40. L

    How Do You Calculate the Acceleration and Distance of a Box Pulled at an Angle?

    Ive never used this before but my teacher said it worked well. i guess i just write the problem... a 50.0 kg box on frictionless wheels is pulled across the floor by a rope with 68 N of tension. The rope makes and angle of 34 degrees to the ground. calculate the acceleration of the box along...
  41. M

    Calculating Net Force on Mass: 800N, 347N, 0.074m/s/s

    just curious...if someone was pulling me with a rope around my nech, he was exerting a force of 347N, and I weight 800N, what is the net force that is goign to be applied to my mass?? gravity is 0.074 m/s/s because i think to get the net force i need the acceleration (Fn = ma) and here I have...
  42. K

    Net force exerted between hemispheres of uniformly charged sphere

    Find the net force that the southern hemisphere of a uniformly charged sphere exerts on the northern hemisphere. Express your answer in terms of the radius R and the total charge Q [the "model" answer is \frac{1}{4 \pi \epsilon_0} \frac{3 Q^2}{16 R^2}] my attempt: regard two hemispheres...
  43. J

    Pressure in a tornado and net force on a door

    In a tornado, the pressure can be 15% below normal atmospheric pressure. Seomtimes a tornado can move so quickly that this pressure drop can occur in one second. Suppose a tornado suddnely occurred outside your front door, whic is 182cm high and 91cm wide. what net force would be exerted on the...
  44. E

    Pressure and Net Force Question

    I'm working on my homework, and I have finished all the problems save for one. I think I am on the right track, but I'm lacking just a few bits of info. Here is the question (it has 2 parts, I have answered the first part correctly, but cannot get the second part correct). Part 1...
  45. J

    Net Torque & Net Force: Exploring the Relationship

    if there is a net torque on a system does that mean there must be a net force on the system
  46. F

    Calculating Net Force on an Object Moving Up an Incline

    Whats the net force of an object going UP an incline? I don't have an applied force, just the velocity, mass, and coeffieciant of friction. I solved for the Force of friction but how do i solve for Fnet? I don't think its Fnet = Fg(parralel) - Ffriction cause Fg is still pulling down?
  47. C

    Newton's Laws and Net Force: Checking My Understanding

    please help me check my answers, cause if i get one answer wrong, it's a big point deduction. i don't really like doing my homework online. here it goes... 1.) An object cannot remain at rest unless which of the following holds? A.)The net force acting on it is zero. B.) The net...
  48. P

    Calculating Net Force: Equilateral Triangle with Point Charges

    Hi, Can anybody help me get started on this problem? Point P2 is located 3.0 m away from each -Q (-Q = -40 nC) , forming an equilateral triangle with them. Determine the net force (magnitude and direction) that would act on a small charge of +1.0 nC placed at P2. Any hints? Thanks!
  49. G

    How can you determine the net force of a bottle

    How can you determine the net force of a bottle who's contents are kept under 2 atm of pressure, and it has a 1 cm opening for example? a1v1=a2v2 doesn't seem to apply, and the flowrate=dav doesn't seem to either. I suspect it is bernoulli's equation, but I am unsure. I know P=F/A, but how...
  50. B

    Net Force on q5: Magnitude & Direction

    assume the charges 1-4 are fized ( q1=+3uC, q2=+4uC, q3=-3, q4=-4) Find the net force felt by charge 5 (q5=-2uC) both magnitude and direction. I'm not sure wut equation to use?
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