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. Q

    Help With Net Force Formula and Newton's Second Law

    Homework Statement 1. Compare the mass of the system to the slope. Does your data support Newton's Second Law? 2. Using the words "directly" or "indirectly" briefly explain how force, mass, and acceleration are related to each other, making specific references to the parts of the...
  2. B

    What Is the Charge of q2 When the Net Electric Field at Point P Is Zero?

    Homework Statement Two point charges, q1 and q2, are placed 0.30m apart on the x-axis, as shown in the figure(http://hiviz.org/apb89/ap/problems/2006-3.jpg" . Charge q1 has a value of -3.0x10^-9 C. The net electric field at point P is zero. A) What is charge of q2 (Positive/Negative) B)...
  3. K

    Electric force problem (determining unknown position to make zero net force)

    Homework Statement A +2.0-nC charge is at the origin and a -4.0-nC charge is at x = 1.0-cm. At what x-coordinate could you place a proton so that is would experience no net force? [NOTE by me] I put q1 as the positive charge (+2.0nC) and q2 as the negative charge (-4.0nC). q0, of course...
  4. O

    Finding Net Force: Solve w/ F=ma

    Homework Statement Homework Equations F=ma The Attempt at a Solution According to Newton's 3rd law, the box pushes back on the person 36N. But I don't know how you find how much force the smaller crate exerts on the larger one.
  5. P

    Finding net force on object with more than one force

    Homework Statement Three 8kg spheres are located at (0, 1.7), (1.7, 1.7), and (1.7, 0) named A, B, and C respectively. What is the net gravitational force acting on sphere A? Homework Equations F = GMm/r2 The Attempt at a Solution So far I've tried this several ways with no...
  6. K

    Net Force of Point Charges, Coulomb's law

    Homework Statement The drawing shows three point charges fixed in place. The charge at the coordinate origin has a value of q1 = +8.02 C; the other two have identical magnitudes, but opposite signs: q2 = -4.73 C and q3 = +4.73 C. (a) Determine the net force exerted on q1 by the other two...
  7. R

    What is the Net Force on an Angled Surface in a Limited Force Scenario?

    I prepared a drawing to reference what i am trying to explain: http://i20.photobucket.com/albums/b225/rush02112/part1.jpg I will have pressure acting against the all surfaces of this part. Notice this part will only be able to move parallel to the center line of the part. I want to know...
  8. P

    Conceptual question regarding net force and velocity

    Homework Statement An object is moving to the right in a straight line. The net force acting on the object is also directed to the right, but the magnitude of the force is decreasing with time. The object will a) stop and then begin moving to the left. b) continue to move to the right...
  9. P

    Net Force of Car: Solving for 70kg Driver Deceleration

    [b]1. The problem statement, A driver wearing a seatbelt decelerates at roughly the same rate as the car itself. Since modern cars have a "crumple zone" built into the front of the car, the car will decelerate over a distance of roughly 1.0 . Find the net force acting on a 70-kg driver who is...
  10. N

    Calculating Net Force on 2kg Mass Down 8m Incline

    Homework Statement A 2kg mass starts from rest and slides down an inclined plane 8.0X10m long in 0.50s. What net force is acting on the mass along the incline? Homework Equations The Attempt at a Solution I don't even know where to begin.
  11. H

    What Forces Affect the Acceleration of an Airboat?

    An airboat with mass 4.38 102 kg, including passengers, has an engine that produces a net horizontal force of 8.08 102 N, after accounting for forces of resistance. a>how long does it take the airboat to reach a speed of 16.0 m/s? b>After reaching this speed, the pilot turns off the engine and...
  12. A

    What is the net force on the block immediately after it starts to slide?

    Homework Statement The coefficient of static friction between a block and a horizontal floor is 0.40, while the coefficient of kinetic friction is 0.15. The mass of the block is 5.0 kg. A horizontal force is applied to the block and slowly increased. What is the value of the applied...
  13. M

    Two forces, two angles; Net force = ?

    Greetings everyone! Thanks in advance for the help! Homework Statement Two parts to the problem. For both parts it asks for the magnitude of the net force and the direction of angle from the X axis. Part A: Two forces, F1 and F2, act on an object at rest at a 90* angle. F1 = 30N, F2 = 11N...
  14. K

    Finding zero net force between two charges

    [b]1. Here is the question we were given: There are two charges on a horizontal line of 2 m length. *-----------------------* Qa = +4q Qb = +2q If a third point of charge "q" is moved between these points, where will the forces acting...
  15. D

    Moving a block with kinetic and static friction to find the net force?

    The coefficient of static friction between a block and a horizontal floor is 0.37, while the coefficient of kinetic friction is 0.14. The mass of the block is 3.4 kg. If a horizontal force is slowly increased until it is barely enough to make the block start moving, what is the net force on the...
  16. P

    Calculating net force on a charge placed at a spot

    Homework Statement Two charges, -16 and +3.4 mC, are fixed in place and separated by 4.4 m. (a) At what spot along a line through the charges is the net electric field zero? Give the distance of the spot to the positive charge in meters (m). (Hint: The spot does not necessarily lie between...
  17. F

    Static and Kinetic Friction Forces (Finding Net Force)

    Homework Statement The coefficient of static friction between a block and a horizontal floor is 0.414, while the coefficient of kinetic friction is 0.138. The mass of the block is 5.24 kg. A horizontal force is applied to the block and slowly increased. What is the value of the applied...
  18. T

    Calculating the magnitude of the net force bewteen charges

    Homework Statement Nine different charged balls, which we treat as point charges, are arranged in a highly symmetric pattern around a square. Note that the value of Q is 4.00 x 10-6C, and L = 30.0 cm Image: http://www.webassign.net/userimages/81224?db=v4net Homework Equations 1)...
  19. B

    Finding the Net Force Exerted by Water (of certain depth) on A Dam

    Homework Statement Evaluate the net force on a 200 -m high dam with a 60 mwater depth. Homework Equations P=F/A p(hydrostatic pressure)=rhogh+patm The Attempt at a Solution The atmospheric pressure acts on both the dam and the water, so it cancels out of the equation. g=9.8m/s^2...
  20. D

    Net force exerted on the two-particle system

    net force exerted on the system quick question- halllp lol. Homework Statement The vector position of a 3.10 g particle moving in the xy plane varies in time according to the following equation. r1 = (3i+3j)t + 2jt^2 At the same time, the vector position of a 5.15 g particle varies...
  21. B

    Pressure, force, and Area: Calculating the net Force Applied on A dam by Water

    Homework Statement Water stands at depth d behind a dam of width w . Find an expression for the net force of the water on the dam. Express your answer in terms of the variables w,d,p (density), and appropriate constants. Homework Equations P=F/A or pressure=Force/Area Hydrostatic...
  22. S

    Is Centripetal Force the Only Force in Space-Based Circular Motion?

    I'm doing a lab, and I need to determine the centripetal force of a ball tethered to a string, rotating around at a constant acceleration horizontally. In this instance, is the only force in the problem the centripetal force, in which case would also be the net force, or is there also a normal...
  23. R

    What is the net force on the roof

    Homework Statement If wind blows at 35 m/s over a house, what is the net force on the roof if its area is 240 m2 and is flat? Homework Equations Pat + 1/2 * pair * v^2 The Attempt at a Solution wind velocity - v - 35 area of roof - A - 240 density of air - p - 1.29 atmospheric...
  24. B

    Calculating the Net Force Vector for Multiple Force Vectors

    Consider 3 force vectors F1, F2, and F3. The vector F1 has magnitude F1 = 36N and direction θ = 110°; the vector F2 has magnitude F2 = 22N and direction θ = - 140°; and the vector F3 has magnitude F3 = 28N and direction θ = 20°. All the direction angles θ are measured from the positive x axis...
  25. A

    Newton's second law net force = mass

    Homework Statement True or false: "Given that the same force acts on particle A and B, If object B covers the same distance in less time than particle A, object B is less massive than object A" Homework Equations net force = mass(acceleration) The Attempt at a Solution I believe...
  26. E

    Net force between two identical dipoles

    Homework Statement I need to find force between two dipoles. I was thinking of finding F between all the four charges separately and then using superposition principle to get the net charge. but is there an easier way. Say, if I use the formula of E (dipole) for one dipole and multiply it...
  27. M

    Average Net Force: Kinetic Energy & Momentum

    This is just a general question- Given a beginning and ending velocity, and distance that the object travels, would the average net force be the change in kinetic energy divided by the distance? (Using energy methods only) I think I've also seen avg force calculated with momentum...
  28. K

    Understanding Centripetal Net Force in Circular Motion

    Homework Statement If you swing a ball in a horizontal circle around your head, what is the direction and magnitude of the net force acting on the ball? Homework Equations The Attempt at a Solution I said none because the ball is moving at a constant velocity. Is this correct...
  29. C

    Calculate the net force on the central charge

    Homework Statement A square of side 1cm has a charge of q= 1uC at its center. The four vertices of the square have charges distributed equally. Calculate the net force on the central charge. A. Find the distance from the central charge to the equidistant charges B. Find the force of...
  30. J

    Net Force Questions: Calculating Frictional Force

    Homework Statement A student drags an object across a laboratory table at constant velocity using an applied force of 12 Newtons. Calculate the frictional force 2. a horizontal force of 15 Newtons pulls a 5 kg block along a horizontal surface. If the force produces an acceleration of 2...
  31. T

    Net Force on airplance cabin surface

    Homework Statement 5. The air pressure at sea level on a cold day is P0 = 1.013 x 105 Pa. At 10.0 km above sea level the air pressure is 0.30 P0 ; however a commercial jet plane keeps the pressure in the passenger and crew section at 0.75 P0 . If the surface area of the cabin structure is...
  32. U

    Solving for Speed: Average Net Force & Mass

    1. A beam consisting of around 1.0 1015 electrons per second, each of mass 9.1 10-31 kg, paints pictures on the face of a TV tube. Assuming that the electrons are absorbed by the screen and exert an average net force on it of 0.9 10-7 N, what is their average speed at impact? 2. Favg =...
  33. L

    How Much Force to Slide a 10 kg Box with Friction?

    Homework Statement A 10 kg box rests on a horizontal surface. The coefficient of static friction is 0.85. If a force is applied to the object at 30° above the horizontal, what is the minimum magnitude this force must have in order for the box to slide? Homework Equations Fnet = ma Fs = usFn...
  34. F

    Calculating Net Force: 930kg Car & 320kg Trailer with 2.16 m/s2 Acceleration

    Homework Statement A 930 kg car is pulling a 320 kg trailer. Together the car and trailer move forward with an acceleration of 2.16 m/s2. Ignore any frictional force of air drag on the car and all frictional forces on the trailer. determine the net force on the car. Homework Equations f...
  35. N

    What is the Average Net Force on a Diver During a Fall into a Swimming Pool?

    1. Homework Statement [/b] A 76.0 kg diver falls from rest into a swimming pool from a height of 6.9 m. It takes 1.44 s for the diver to stop after entering the water. Find the magnitude of the average net force exerted on the diver during that time.
  36. H

    Net Force of 3 Forces (Equilibrium)

    Homework Statement I need some help with a Physics lab. My teacher wasn't there the only chance I could ask him. I don't understand how to prove that the net force is zero when you have the three forces in different directions. For example, the first force is 9.7 N [down], the second is 5.3 N...
  37. C

    Net force, force diagrams, normal force

    In a problem whereby you want to calculate the net force of the rope lifting a box, and there is something in the box, whether you take into account the normal force. The forcees would be the tension of the rope, and the weight of the box and the object inside. To caculate the net force of the...
  38. C

    Calculate the magnitude of the average net force on the car

    Homework Statement A 1270-kg car coasts on a horizontal road with a speed of 18.1 m/s. After crossing an unpaved, sandy stretch of road 28.4 m long, its speed decreases to 11.3 m/s. Was the net work done on the car positive, negative, or zero? b. Calculate the magnitude of the average...
  39. X

    What is the Net Force on a Helicopter at 5 Seconds?

    The position of a 2.75x10^5N helicopter under test is given by r=(0.020m/s^2)t^3i + (2.2m/s)tj - (0.060m/s^2)t^2k Find the net force of the helicopter at t=5.0s express the vector F in the form Fx, Fy, and Fz so far i plugged in 5.0 to each component in the r equation which gave me...
  40. D

    What Is the Definition of Net Force?

    Please tell me the definition of NET FORCE Thanks!:smile:
  41. X

    Find Net Force of 2.5x10^5N Training Helicopter

    The position of a 2.5x10^5N training helicopter under test is given by r=(0.020m/s^3)t^3i + (2.2m/s)tj-(0.060m/s^2)t^2k , find the net force of the helicopter at t=5.0s express F in the form Fx Fy and Fz F=ma F=Fx+Fy+Fz so far i plugged in t to each component to get 2.5m, 11m, and...
  42. M

    Direction of the net force on the charge

    I drew these pictures, so some letters came unclear, I will clarify them later in parentheses. Chp9,46, the diagram represents two small charged spheres, A and B, 3 meters apart. Each sphere has a charge of +2.0*10^-6 coulomb. (The point in the middle is y) If a positive charge is placed at...
  43. E

    Calculating Net Force on a Tilted Object: A Vector Analysis

    Homework Statement Three forces are exerted on an object placed on a tilted floor in the figure (Intro 1 figure) . The forces are measured in Newtons. (Figure attached below) a) Assuming that forces are vectors, what is the component of the net force parallel to the floor? B)What is...
  44. J

    Position three point charges so net force is zero

    Homework Statement li have three charges, 2 with same charge (magnitude and sign) and 1 with a smaller charge(smaller magnitude and opposite sign to the other two). how would i position them on a line so that the net force on any of them is zero Homework Equations electric force, F =...
  45. J

    Finding charge based on net force and other charges

    Homework Statement Blue charge is at origin with positive q charge Red charge at point (d1,0) with unknown positive charge q_red Yellow charge at point (d2cos(theta),-d2sin(theta)) with negative 2q charge The net electric force on the blue sphere has a magnitude F and is directed in the...
  46. G

    Finding net force on charges on xy plane

    Homework Statement A proton is on the x-axis at x = 1.2 nm. An electron is on the y-axis at y = 1.2 nm. Find the net force the two exert on a helium nucleus (charge +2e) at the origin. Express your answer using two significant figures. Enter your answers numerically separated by a comma...
  47. R

    What is the Direction of Total Force Acting on an Object?

    This is a fairly simple Question but I just can't figure it out. If there is an object and there are two forces that act on the 5 kg object (say this object is located on the origin of an sy plane) and F1= 25 N and points in the 0 degrees direction and the other force, F2= 15 N and points 60...
  48. S

    STATICS: Chapter 2, net force of lifting a given mass.

    Homework Statement "A derrick boom is guyed by cables AC and AD. A worker is lifting a 20kg block by pulling on a rope that passes through the pulley at A. Knowing that the boom AB exerts a force A that is directed from B to A, determine this force and the force in each of the two cables."...
  49. K

    Calculating Net Force Between Two Dipoles

    Homework Statement Two identical dipoles, each of charge q and separation a, are a distance x apart, as shown in Fig. By considering forces between pairs of charges in the different dipoles, calculate the net force between the dipoles. Show that, in the limit a<<x, the force has magnitude...
  50. S

    Net Force on Particle 0 from Particles 1 & 2

    Two positive charges q0 at the origin and q1 at (0,d1,0) and one negative charge -q2 at (0,d2,0). What is the net force on particle 0 from particle 1 and 2? (See Picture CPartB inserted at bottom) F on 0 due to 1 = kq0q1/d1^2 and since it is in the negative y direction since q1 repels q0...
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