# What is Resultant force: Definition and 172 Discussions

In physics and engineering, a resultant force is the single force and associated torque obtained by combining a system of forces and torques acting on a rigid body. The defining feature of a resultant force, or resultant force-torque, is that it has the same effect on the rigid body as the original system of forces. Calculating and visualizing the resultant force on a body is done through computational analysis, or (in the case of sufficiently simple systems) a free body diagram.
The point of application of the resultant force determines its associated torque. The term resultant force should be understood to refer to both the forces and torques acting on a rigid body, which is why some use the term ' resultant force-torque.

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1. ### Engineering Resultant Force and Direction using Parallelogram Law

Picture above is the complete question. I want to ask about the problem where I would use the parallelogram method. Here is my FBD: I start off by computing the angle alpha: α + α + 105 +105 = 360 α = 75 degree After that, I now use cosine law to solve for the resultant force...
2. ### Determine the point of application of a resultant force

I am struggling with part b of the question attached in the screenshot. For part a, I simply add the components of the given forces. I tried calculating the moments using vector cross multiplication, but I don't know what to do after that or even if that step is useful.
3. ### Resultant force and centre of pressure in a tank

Figure: a) CASE A ##\rightarrow p_a=101300\, \textrm{Pa}## $$F_{\textrm{res}}?,\,\, y_c-y_{cg}=y_{cp}$$ We find ##h_{cg}\rightarrow h_{cg}=3+h## $$h=0,75\cdot \sin (30)=0,375\, \textrm{m}\rightarrow h_{cg}=3,375\, \textrm{m}$$ $$p_{cG}=\rho_{H2O}gh_{cg}=33108,75\, \textrm{Pa}$$ We calculate...
4. ### Resultant pedal force (FRESULTANT) Force tangential to the crank arm

%% part 1 clear all; close all; clc; torq_crPK = zeros(10,1); ang_tqPK = zeros(10,1); ang_powPK = zeros(10,1); torq_crDS = zeros(10,1); torq_crUS = zeros(10,1); WD = zeros(10,1); WDpos = zeros(10,1); WDneg = zeros(10,1);%% INPUT VARIABLES for i=1:10 % cyclist number % read in the...
5. ### B Resultant force in vertical circular motion

Suppose we have a vertical circular motion with gravity according to the image below. In the leftmost and rightmost positions the resultant force is pointing diagonally down. Isn't the resultant force supposed to be pointing at the center at all times in a circular motion? What am I getting...

7. ### Question about how to calculate the Resultant Force at this point

Hello all Trying to solve this one, faced a dilemma if i should trasfer the 5N vector from third to first quadrat becuase it head is on the 0 axis ass opposed to the two other vectors. If it remains in third quadrant its components eouls be both negative, if transferred to first quadrant both...
8. ### Calculate resultant force of a linear mechanism

Hi all, I'm currently designing a linear to linear transform mechanism (wedge cam design). Would like to check how much force required to push/ slide the roller down. To ease calculation, i have include some assumption: F2 = 1kg @ maximum compressed angle = 20degree F1 required = ? and how...
9. ### Finding the resultant force using a vector polygon diagram

Hi I made an attempt at this problem but have got the wrong answer The correct answer is actually resultant force = 21.767 N at 61.34 degrees (or 151.34 degrees bearing), but I don't know how they got that? Any help would be appreciated! Thanks

11. ### Electric Fields: calculate the resultant force

Summary:: I try to find the resultant force on "q". I think I have to find the value of Q, but I'm not sure. I Know F1 = k|q * 2Q| / 3² and F2 = k|q * Q| / 2² Hi, this is my first post on this forum I hope I posted in the right section. I try to find the resultant force on "q". I think I...
12. ### What is the magnitude of resultant force on a car on a banked curve?

Ok so I think that the equation for centripetal force is the mv^2/r and this SHOULD equal the horizontal component of the normal force on the car. Vertical component of normal force and gravity would cancel out. However, when I input the numbers into the equations I don't get equivalent values...
13. ### I have two doubts in this equilibrant problem (resultant force)

Two forces are pushing an object along the ground. One force is 10 N [W] and the other is 8.0 N. Sketch a diagram showing the equilibrant of these two forces, and determine the equilibrant. Ans) Calculate the equilibrant... C2 = a2 + b2 = 102 + 82 c = 13 NDiagram: tanΘ = opp/adj = 10 / 8...
14. ### I Wrong solution in the book? Calculating force projection.

The question asks to calculate the determine the projection of the resultant force of F1 and F2 onto b-axis. However instead, the solution is a projection of F1 on b axis plus F2. Shouldn't the solution involve the projection of R which is 163.4 on to be axis? and for answering that, don't we...
15. ### Hydrostatics Pressure - Finding thrust and resultants

Homework Statement I'm getting stuck with this one and in need of some direction! Obviously I'm not looking for a direct solution, but maybe a outline of what I should be doing? (I'll attach an image in a few minutes) <Image here incoming!> Known data: d2 = d1 / 2 F = thrust force (N) Pa = ρ...
16. ### Finding the angle in which the resultant force points

Homework Statement Forces of 11.8N north, 19.2N east, and 15.9N south are simultaneously applied to a 3.93kg mass as it rests on an air table. What is the magnitude of its acceleration? What is the direction of the acceleration in degrees? (Take east to be 0 degrees and counterclockwise to be...
17. ### B Force Resultant is equal to the sum of the components -- why?

Why are the resultant's X and Y components of two forces equal the sum of the X and Y components of the two forces?
18. ### Fluid Mechanics: resultant force of oil and water on a door

Homework Statement Homework Equations The Attempt at a Solution [/B] My questions: 1. By resultant force, does that mean the force exerted on the side of the water + force exerted on side of the oil? Because I'd think that the force on the side of the water would be different than the...
19. ### Resultant force from water on dam

Homework Statement : [/B] The cross-sectional profile of a dam is shaped as an isosceles triangle. The dam is standing on horizontal ground and the watermirror is as high as the top of the dam. The dam has height h, length l and the distance from the bottom to the watermirror along the dam's...
20. ### I Calculate the Resultant Force Between 4 Points

I am trying to figure out how to calculate the resultant force between 4 anchor points. Basically I want to hang two kayaks on two ropes suspended across a room. Below I have some crudely drawn images of the set up: I found how to calculate the vector forces between two points as pictured...
21. ### Vector addition and the force applied to the shaft of the pulley

Homework Statement Hello, I am currently studying mathematics and physics on my own, and I ran into a type of problem in physics that is a bit unclear to me. Say we have pulley at the top of an inclined plane with a base angle of alpha and the top angle is alpha. Homework Equations I assume...
22. ### Resultant force of spring at the instant of release?

Homework Statement What would the resultant force have been at the instant of release, if a 350 g mass were suspended from your spring, pulled down 3 cm and released? What would have been the instantaneous acceleration at the moment of release? The questions pertain to an experiment with a...
23. ### B Direction of Resultant Force on a Skydiver After Opening Parachute

When a skydiver falls at terminal velocity, and opens his parachute, what will be the direction of the resultant force immediately after he opens his parachute? As far as I know is that the direction of acceleration will be upwards since his velocity is decreasing. I am a bit confused regarding...
24. ### Resultant force and its point of action

Homework Statement A storage tank has the cross-sectional shape shown attached and is of 1m breadth. Calculate the resultant force acting on the inclined surface AB and its point of action. The density of the liquid is 900kgm–3 and take g = 9.81ms–2. Homework Equations P = ρgh F = ρA Point...
25. ### Why must we use integral to find the resultant force?

Homework Statement Hydrostatic force on a plane surface ex: Hydrostatic force on a gate: Homework Equations The Attempt at a Solution why can't we just use the formula in the red box above for problem 3.57? instead I have to use integral I am confused, how does this gate different from...
26. ### How can I draw the resultant force of the couple M, F1 and F2?

I'm supposed to express the reultant force R of M, F1 and F2 in terms of F1, F2, r, s and α. But I need to know how to draw R first. How can one do this? Does the couple create a force uppwards from O? Can I move F_1 and F_2 also to the origin and combine the forces? Here is the image:
27. R

### Resultant Force and Acceleration of Space craft

Homework Statement https://isaacphysics.org/questions/gcse_ch2_13_q10 https://www.physicsforums.com/attachments/213735 https://i.imgur.com/WnZkt83.jpg The thrust generated by a rocket engine is equal to the mass of propellant burnt each second multiplied by the exhaust velocity of the gas...
28. X

### 2 unknown Forces+known resultant force

Homework Statement Hi, I'm having trouble with my first mechanics assignment and I'd appreciate some help. So, an object is being pulled using two ropes (Fa and Fb) with a resultant force of 970 N along the x axis. The angle from Fa to the axis is 20 degrees, angle from fb to the axis is 51...
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### Calculating Unknown Forces in a Vector Diagram

Homework Statement Hi, I'm having trouble with my first mechanics assignment and I'd appreciate some help. So, an object is being pulled using two ropes (Fa and Fb) with a resultant force of 970 N along the x axis. Angle from Fa to the axis is 20 degrees, angle from fb to the axis is 51...
30. T

### How to calculate resultant force for a bike pedal stroke

Homework Statement To calculate the resultant pedal force from the variables given: Crank (degrees) measured clockwise from vertical, spindle (degrees) measured anti-clockwise from horizontal, tangent force (N) applied to the pedal surface, normal force (N) applied to the pedal surface and...
31. ### How to find the resultant force in a T tube section

Homework Statement So, I need to find the X and Y components of the force in the T section Homework Equations Due the fact that the problem dosn't ask for a specific force I couldn't think in any other equation to use, because even tough there is Pressure and Gravity acting I need to...
32. ### Finding Resultant Force Using Cosine and Sine Law

Homework Statement "Calculate the net force with the resultant angle acting on each object indicated in the diagram." The line going off to the southeast is supposed to be straight. My computer art skills aren't great. | 22 N | |_ _ _ _ _ \ ) 35 degrees \ \ 38 N 2...
33. ### B The Sense of Restoring Force in Vibrations

I would like to ask about the sense of the restoring force in mechanical vibrations. Comment 2 says that resultant force is opposite the motion but I have some hesitations about it because let's think the situation that mass is moving back upward to its equilibrium position. In this case the...
34. ### Magnitude & Direction of Resultant Force & Equilibrant Force

Homework Statement I need help as to how to find the magnitude and direction of the resultant force, and the equilibrant force. Any and all help is greatly appreciate as I'm stressing myself out over it and I'm not sure what to do. Thanks, Jamie. Homework Equations First question...
35. ### Body of mass m is accelerating -- Need to find resultant force

1. Body of mass m = 3kg is accelerating with acceleration of ##\vec a = 2\vec i + 5\vec j m/s^2 ##. I need to find the resultant force ##\vec F## and the force's value. 2. Of course, the first equation that came to my mind is ##\vec F = m * \vec a## 3. I came with a possible solution for this...
36. ### I Resultant force after adding a force to a couple moment?

I don't get it. Imagine there is a stick leaning aganist a wall. There is a moment couple somewhere on the stick. The end of the stick hits the wall and the wall acts against it. The sum of moment is 0 but since the moment couple forces cancel each other, the resultant force is the wall...
37. ### Quick Resultant Forces Question

Homework Statement So we have 65N @ 30*, 30N @ 180* and 20N at 250* Homework Equations Ncos(angle)i + Nsin(angle)jThe Attempt at a Solution Using this video I did the following. F1(65N) = 65cos(30)i+65sin30i Then using the radian circle I saw that 30* has x,y coordinates of sqrt3/2...
38. ### Are resultant force and total force the same?

Homework Statement The wall shown in Fig. 4.28 is 20 ft long. Calculate the total force on the wall due to water pressure and locate the center of pressure Homework Equations Are resultant force and total force the same? The Attempt at a Solution I think they are not the same because resultant...
39. ### Forces Due to Static Fluids

Homework Statement Find height (h) of the water level which can result in failure of dam by tipping it over due to water pressure at U/S of dam. Also draw the free body diagram. Density of water to be = 1000 kg/m^3 and its specific weight=62.4 lb/ft^3 Hints: The specific weight of concrete is...
40. ### Resultant Force and its Components

Homework Statement The Resultant of the system of forces shown is R = 425 j lbs. Determine the possible values of P and Θ. Homework Equations R = F1 +F2+P The Attempt at a Solution I ended up with two equations, one in the "i" direction and one in the "j" direction. I think you have to use...
41. ### What is the Direction of Resultant Force on a Stationary Vane Caused by Water?

Homework Statement in the calculation , the direction of resultant force that we got is the force of vane act on water , right ? to get the resultant force act on vane ? it should be opposite to the force of vane act on water , am i right ? IMO , the resultant force at stationary vane (which is...
42. ### Is the direction of resultant force to the left in this problem?

Homework Statement i am confused about the direction of resultant force . in the working ,it's clear that the author taking to the right as positive , for the force component along x-axis , we have -Fx , but , in the calclulation , we gt positive 32230N , so the resultant force of x-component...
43. ### Resultant force at elbow from water flow

Homework Statement water flows in an elbow was aligned horizontally , of angle 135 degree . If the water volume is section 1 and 2 is 0.2m^3 , the elbow is 12kg , flow rate is 0.4(m^3)/s , find the resultant force Homework EquationsThe Attempt at a Solution i found x and y component of the...
44. ### Direction of resultant force

Homework Statement why the resultant force on blade is acted downwards (toward A)? why shouldn't it be slanted upwards ? since the horizontal component of the force acted 2.12kN to the left , and 0.735kN upwards , we would get the resultant force acting slanted upwards , right ? Homework...
45. ### Calculate the average resultant force required to accelerate the ball.

Homework Statement A 56 g tennis ball is accelerated at 1000 m s-2 to reach its service velocity. Calculate the average resultant force required to accelerate the ball. Homework Equations F = MA The Attempt at a Solution Mass = 0.56g = 0.056kg Acceleration = 1000m/s2 0.056 x 1000 = 56N...
46. ### Circular Motion and resultant force

Homework Statement Homework Equations F= mv^2/r v = angular vel* r The Attempt at a Solution resultant force= ma-frictional force = mv^2/r - mg*meu = (angular vel)^2mx - mg*meu But then how do I get the angular speed when I don;2 know the resultant...
47. ### STATICS problem: Minimum Resultant Force

Problem Statement: If the resultant force acting on the bracket is required to be a minimum, determine the magnitude of F1 and the resultant force. Set ∅=30 deg. I have found the components of each force and set them up into a resultant vector, with F1 solved symbolically into its...
48. ### Equivalent Resultant Force for Distributed Load: Is My Method Correct?

Homework Statement i am asked to find the equivalent resultant force for this question . for the distributed load , i divided into 4 parts , is my method correct? Homework EquationsThe Attempt at a Solution total force about y = 6sin30 + 3(3) + (5-3)(0.5)(3) + 5(4) + (7-5)(4)(0.5) total...
49. ### How large is the resultant force on Gavin's toy car after he kicks it?

Homework Statement Gavin is kicking one of his toy cars with a force straight ahead. the car weighs 1.2 kg and has friction free wheels so that the friction forces of the car is small when it has started. Gavin kicks his car with the force of 2.4 N. How large is the resultant force? Homework...
50. ### Finding Resultant Force using Component Method

Homework Statement This is the force table lab that we are doing. F _1 = 300g @ 30^o F _2 = 450g @ 110^o F _3 = 400g @ 230^o F _4 = 270g @ 298^o Finding resultant force using Component Method 1. Express each force F1, F2, and F3 in unit vector notation. Take the origin to be at the center...