# What is Net force: Definition and 504 Discussions

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. ### Motion of a Parachuter (Terminal Velocity, Time of Flight, Distance)

(a) -98 m/s (b) 490 m (c) My understanding is that at terminal velocity the net force in the y direction must be zero. Therefore: F_y = ma = 0 Only drag and weight forces act on the skydiver so: F_D + mg = 0 F_D = -mg -0.75*v = -82*(-9.8) v = -1071.5 m/s The value I get for v appears to...
2. ### Calculating Net Force on a Wheel: Magnitude and Direction | 0.350 m Radius

Three forces are applied to a wheel of radius 0.350 m, as shown in the figure. One force is perpendicular to the rim, one is tangent to it, and the other one makes a 40.0 degree angle with the radius, and a 10 degree angle with the horizontal. a) What is the magnitude of the net force on the...
3. ### Change in momentum: Child jumping from a swing on a playground

800 - (32 x 9.8) = 32v/0.18 where v = velocity this gives me v = 2.736 m/s The answer given, however, is 800 = 32v/0.18, i.e. v = 4.5 m/s The difference, of course, is the weight of the child. I don't understand why this is not allowed for in the net force acting on the child. Can someone put me...
4. ### Solving for Tension in Net Force Equation: Need Help!

I have tried finding the tension of the string through the equation Net Force = T - mg = ma but I am struggling with coming up with the correct acceleration. Is my net force equation correct?
5. ### Calculating Net Force of 3 Blocks in an Elevator

m1 = 4 kg, m2 = 12 kg, m3 = 8 kg. k = 327 N/m for all three blocks. The elevator accelerates upwards at 3.8 m/s^2. Net force of block one would be equal to force applied by top spring minus weight of system, since top spring is holding all 3 blocks. F1 = 4*3.8= Fs,top - Wsystem = Fs,top -...
6. ### I If there is no force being applied can there still be a net force?

If there is no force being applied can there still be a net force? For example, supposed you apply a force F forward on an object on a frictionless plane, the moment you stop applying the force, the object may still be accelerating towards its final velocity but there is no applied force. So if...
7. ### Net Force of A: Diagram Analysis

Find the net force of A as shown in the diagram.
8. ### Net force and position of objects in space

Q1a) - My current wrong answer is <-5.9e7, -3.3e8, -2.17e8> I used the Fnet = Gm1m2 / d^2 <unit vector> But i keep getting a dif answer each time Q2a) - I thought i could find net force and then divide it by the mass, and multiply it by the time interval. However I got the answer <-4.5, 4.5...
9. ### I Positive Charges: Explaining Motion Despite Net Force = 0

in a cours of electrostatic when we have a positive charge and we bring another one (also postitive)we have to do work and apply a force that equals the force of repultion over the distance which seems weird because if we do that the net force will be equal to 0 and the charge will not move can...
10. ### I am calculating the forces on String cheese with net force = 0

Here is the link to the question. https://www.khanacademy.org/science/physics/forces-Newtons-laws/Newtons-laws-of-motion/a/what-is-Newtons-second-law What is the magnitude of the force F1 ? What is the magnitude of the force F2 ? Here is my drawing I made At this step I am lost. ## ay...
11. ### Finding the position of a middle charge to have Zero Net Force

Hi! Given three voltages as follows; Q1 = 1C,Q2 = 1C,Q3 = 2C The distance a is 1m and b = 2m a) Find the values of the forces that are acting on Q2 I did that like this; $$F_{12} = \frac{Q1*Q2}{4\pi\epsilon r^2}$$ $$F_{32} = \frac{Q1*Q3}{4\pi\epsilon r^2}$$ The results are ...
12. ### Effect on net torque and net force on spools

I think both spools will land about at the spot x (there aren't any horizontal forces causing them to land away from the x). Also, I think student 2 might be the closest to being correct, but I'm not sure if they're entirely correct; isn't it possible that force doesn't only go to translational...
13. ### About steel balls of different masses and net force

I don't understand why the answer is B. Here's my thinking: Since it wasn't mentioned that there's any other force aside from the drag force, then Fnet = Drag force I know that Fnet = ma, and since they have different masses, Fnet must be different for both balls? Acceleration cannot be...
14. ### Block on a Spring, Nonconstant Net Force

Just to be clear, this isn't a homework problem. it is an example problem found on page 68 of the text "Matter and Interactions" 4th edition. The solution is given in the book, but I'm having difficulty following their reasoning. according to the book the net force is not constant, therefore we...

16. ### Understanding the Net Force on a Snorkeler's Eardrum

Can someone help me understand what I did wrong when solving this problem?
17. ### Exploring the Equilibrium of a System: Net Force & Net Work

In the solving portion of the textbook, the reasoning of the author in solving this problem is that the net work done on the system is zero because the net force of the system is zero. So my question is how was the system in equilibrium (net force=0)? My thinking is that since it is stated...
18. ### Fundamental Forces Problem: Net Force from Gravity

So what I did was find each of the forces the masses had on m1 using the above equation. From m2 I found 19.975 in the negative i hat and for m4 i found 29.96 in the positive k hat direction using the above equation. For m3 I used pythagorean theorem to calculate r, which was 3.25 (so r^2 was...
19. ### Fundamental Forces: Placing charges along a line so that the net force is zero at a point

So 0=q1q3/r+q2q3/(13.6-r) 0=-8.5/r-3.63/13.6+3.63/r 0.2669=3.63/r-8.5/r r=-18.2465, but the answer is supposed to be 8.24
20. ### Net force acting on a ping-pong ball

w= 0.50N, Fn= 7.8N, angle= 29 Fnet= Fn*fd* costheta = 7.8*0.50*cos(29 = 3.41 is my answer correct
21. ### Determining net force and acceleration

Hi All, Please see attached photo of the question. It is asking for net force and acceleration. Taking the forces acting upwards and downwards on the parachutist as vectors: for A the net force would be 800-300=500; B would be 0 and C; would that be 800-1500=-700? And if so would that imply...
22. ### Net force and moment on a wooden bar fixed at one end

Here is the diagram to the right. (a) Clearly, owing the fact that the bar is pinned at P, the net force on the bar is zero: ##\boxed{\Sigma \vec F = 0}##. The pin P applies an equal and opposite force to the one applied. This force keeps the bar from translating to a different position in...
23. ### Work-KE theorem and net force....

Hello, Just refining my understanding of the work-KE theorem and seeking some validation: The work-kinetic energy theorem states that the mechanical work done by a force (be it conservative or nonconservative) is always equal to the change in kinetic energy of the body. The net force in a...
24. ### Solving Net Force with (g), sin(θ) & μcos(θ)

Tried net force = (g)sin(θ)- μ(g)cos(θ)
25. ### Net force on a Submarine Window?

I have no idea, I honestly thought that the net force would be zero since the submarine window isn't moving...yikes
26. ### Calculating Net Force of Particle 5: A Problem Overview

I have the following problem: So, I know the following: ##q_1 = -e## ##q_2 = -e## ##q_4 = -e## ##q_5 = e## ##e = 1.6*10^{-19}## ##k = 9*10^{9}## Now, I can get the current ##F_{net}## of particle 5 with this information: ##F_{net} = (F_{3} - F_{1})\hat i + (F_{2} + F_{4})\hat j## ##F_{1} = k...

28. ### Direction of the net force acting on a pendulum

I imagine y - axis is parallel to direction of A and x - axis is parallel to direction of E. There are two forces acting on the pendulum: tension in direction of A and weight in direction of D. I break the weight into 2 components: W sin θ in opposite direction to tension and W cos θ in...

30. ### Is this the proper method to find net force?

c^2=a^2+b^2-2abcosC°1/2 = 32^2 =38^2 - 2(32)(38)cos35(0.5) = 2468-995.904 = √1472.096 = 38.36 N tanΘ= 32/38 tan= 0.842 = 40° This is my attempt, I am not sure that I am understanding these formula right
31. ### Tension, Net Force, and Acceleration relationship?

Okay so I am having trouble understanding the relationship between Tension, Net Force, and Acceleration. For example, if two objects in a system are connected by a tension force and accelerating at the same speed, but with different forces acting on each object, would: 1. The net force be equal...
32. ### Net force as a function of time?

All I've done so far is think about F_net. Since F=ma, and a is a vector, I was thinking that I should find the x and y components of a and then try to calculate F_net that way, but I'm confused as to where I should use x(t) and y(t). Or instead, thinking about it as the change in momentum over...
33. ### Net force acting on a charged particle ##+Q##

Homework Statement Twelve equal particles of charge ##+q## are equally spaced over a circumference (like the hours in a watch) of radius R. At the center of the circumference is a particle with charge ##+Q##. a) Describe the net force acting over ##+Q##. b) If the charge located at...
34. ### Finding the mean net force during a collision

Homework Statement Homework Equations F=ma=mv/t[/B] The Attempt at a Solution I used the equation F=mv/t, in which I find the change in velocity and change in time before and after the collision. The change in time is t2-t1, but the problem comes when I am calculating the change in...
35. ### Which answer is correct? Grocery Bag Net Force Question

Today, my class had a dispute between who was right. Two answer keys for this problem was provided, so nobody knows the exact answer to this problem. Half of my class said 100 N while the others said 298 N or something. We won't talk about how I wasn't listening to that because I was trying to...
36. ### Determining net force using Gauss' Law

Homework Statement We have a uniformly charged, non-conducting sphere (charge per volume,ρ, and radius, R). Then a uniformly charged ruler (charge per length,λ, and length, d) is aligned radially almost touching the surface of the sphere. Determine the net force experienced by the ruler...
37. ### Net force on an object and its motion....

Every object continues in a state of rest or of uniform speed in a straight line by zero net force. is this statement correct?
38. ### How does a the vertical force of gravity end in horizontal motion?

When a stream of water falls perfectly vertical, some water hitting the surface will disperse horizontally. What is the force that causes this? References would be awesome!
39. ### Where must a third charge be placed to get a net force of 0

Homework Statement A charge of +2 Q (A)is placed at the origin of a coordinate system and a charge of - Q (B) is placed at a distance d from the origin. How far from the origin must have 3rd charge +Q (C) be placed so that the net force on it is zero Newtons. Homework Equations Fe=kQq/r^2...
40. ### Confirmation of a net force calculation from a diagram

Homework Statement Calculate the net force acting on the object indicated in the following diagram. Show your work. Homework Equations cosine/sine law The Attempt at a Solution First I subtracted 10N and 8N (since they are forces acting in different directions): -8.0N (S) + 10.0N (S) = 2.0...
41. ### Calculating the net force acting on an object from a diagram

Homework Statement Calculate the net force acting on the object in the following diagram: Homework Equations cosine law / sine law ONLY solving using cosine/sine laws. The Attempt at a Solution First using the cosine law to find the magnitude of the net force: c2=a2+b2-2abcosC c2=122+152-2...
42. ### How do you know that the net force is moving to the right?

Frictionless environment. One block moving from left to right hits another block and their combined weight equals .5 kg. When the blocks collide they become attached by an adhesive. The second block is attached to a horizontal spring attached to a stationary wall. k of spring is 50 Newtons per...
43. ### Verification for Net Force and Vectors?

Hello everyone! I was given the following three questions in my homework, and I had a lot of trouble with them, so I was hoping someone could look them over! If you could just check out my pictures and say "yeah its awesome!" or "nope... [insert helpful answer here]" that would be GREAT. Thanks...
44. ### Finding net force from acceleration, speed and distance

Homework Statement The power driving the railroad engine is switched off. The engine stops, from its speed of 16m/s^-1, without braking in a distance of 1.1km. A student hypothesis that the horizontal resistive force is constant. Based on the hypothesis, calculate the mass of the railway...
45. B

### How to measure net force based on diagram

Could someone explain how to find the net force of an object based on a diagram. For example a 2 people walking with forces labeled weight force, reactant force, thrust and drag on one image all forces are balanced which I know the net force would be zero however on the second image thrust is...
46. ### Understanding Net Force Calculation in Physics Problem #93?

Homework Statement https://imgur.com/HR8ssJq https://i.imgur.com/ZxAZ5NR.jpg (full problem, #93) Homework EquationsThe Attempt at a Solution Look at the diagram with Fg, Fn, and Fb. Then look two blocks above it, with the summation sin(theta)Fg - Fbcos(theta) This makes no sense to me. How is...
47. Q

### Calculation of the net force on a test charge

Homework Statement Homework Equations \overrightarrow{F} = \frac{1}{4\pi\epsilon_0}\frac{qQ}{r^2}\hat{r} The Attempt at a Solution I found to hard summarizing all forces directly adding each to other. The solution of this problem is only matter of drawing the 13-sided polygon and forces...
48. A

### B What is the Net Force on a Banked Curve?

I understand why when deriving the formulas for cars on banked curves, the net force in the Y direction is zero. However, when I google how to derive them, people say that there is a net force greater than zero in the X direction. This is not what my professor says in his explanations however...
49. ### Net Force and Centripetal Force relation

Hello Everyone, Question about the centripetal force: the centripetal force is the name given to the component of the net force acting on the object in a direction perpendicular to the object's trajectory and directed towards the center of the osculating circle. This net force component causes...
50. A

### Net force acting on positive charge

Homework Statement Homework Equations F= (k*q*Q)/r^2 The Attempt at a Solution The answer key gives the answer as D. I thought it was C. If the net electric force acting on P is zero, doesn't that mean that the force between Q1 and P and the force between Q2 and P need to cancel each other...