What is Normal force: Definition and 470 Discussions

In mechanics, the normal force




F

n





{\displaystyle F_{n}\ }
is the component of a contact force that is perpendicular to the surface that an object contacts, as in Figure 1. In this instance normal is used in the geometric sense and means perpendicular, as opposed to the common language use of normal meaning "ordinary" or "expected". A person standing still on a platform is acted upon by gravity, which would pull them down towards the Earth's core unless there were a countervailing force from the resistance of the platform's molecules, a force which is named the "normal force".
The normal force is one type of ground reaction force. If the person stands on a slope and does not sink into the ground or slide downhill, the total ground reaction force can be divided into two components: a normal force perpendicular to the ground and a frictional force parallel to the ground. In another common situation, if an object hits a surface with some speed, and the surface can withstand the impact, the normal force provides for a rapid deceleration, which will depend on the flexibility of the surface and the object.

View More On Wikipedia.org
Recent contents Top users
  1. J

    Gravitational and normal force

    Homework Statement A 60 kg skier is beginning her descent down a 26 degree slope. The frictional force between the skis and the snow is 4 N a) What is the gravitational force the skier exerts on the slope? b) What is the normal force the slope exerts back on the skier? Homework EquationsThe...
  2. N

    Quantifying Inertial Resistance

    Hi! I am having a little trouble with a question asked by a colleague. There’s a ball B with a certain mass M, at rest. A small ball A of mass m is moving with speed v toward M. If m=M, and the collision is perfectly elastic and the two objects perfectly rigid, than we know that A would come...
  3. C

    How to specify the normal force for this example

    1. The problem statement Hi, I just have a quick question on how to find the normal force in this picture on mass 2, http://postimg.org/image/w9sr29ab3/ , the half circle. Its a double pendulum with no friction. Can I assume that the normal force is in that position all the time as the half...
  4. Biker

    How does normal force makes us feel our weight?

    So I have been asking my self these questions lately. I know it is some basics of physics and I should probably know the answer.. Why do we feel weightlessness when we hit the acceleration of gravity (9.8) exactly? Probably so that the surface that we are standing on doesn't need to produce any...
  5. aimen khattakk

    Momentum Ball Collision Find Normal Force

    [Note: Thread moved by moderator] Hi! so I have a question I am unable to do and I've been trying it for 3 hours. The question had 2 parts, i figured out part a but cannot figure out part b. A) A 0.006kg ball is dropped from a height of 4.0m above the floor. Neglecting air resistance...
  6. Z

    Work and Kinetic Energy of a Sled

    Homework Statement A man pulls a 15-kg sled containing a 5.0-kg dog along a straight path on a horizontal surface. He exerts a force of 55 N on the sled at an angle of 20.° above the horizontal, as shown in the figure above. The coefficient of friction between the sled and the surface is 0.22...
  7. A

    Acceleration of wedge due to normal force exerted by block?

    This isn't actually a problem. It is a doubt which I have about wedges according to Newton's Laws Consider a friction less wedge, of mass 'M', inclined at angle θ, placed on a smooth horizontal surface, on which a block of mass 'm' is placed. The block exerts some normal force perpendicular to...
  8. C

    Confusion about type and quantity of force being exerted

    Homework Statement A 500-N person stands 2.5 m from a wall against which a horizontal beam is attached. The beam is 6 m long and weighs 200 N (see diagram below). A cable attached to the free end of the beam makes an angle of 45 degrees to the horizontal and is attached to the wall. a) draw a...
  9. Y

    Why is normal force in a satellite zero?

    Gravity does act on a satellite so why is normal force 0 for an object placed inside it?
  10. R

    At what angle does the normal force go to zero?

    Homework Statement An ice cube is placed on top of an overturned spherical bowl of radius r, as indicated in the figure. If the ice cube slides downward from rest at the top of the bowl, at what angle θdoes it separate from the bowl? In other words, at what angle does the normal force between...
  11. Issy04

    Resolving forces in equilibrium on inclined plane

    Homework Statement Solve for the forces P and N acting on an object in equilibrium on an inclined plane. Weight=10N, angle is 30 degrees http://blob:https%3A//www.physicsforums.com/d431a152-5681-411b-ba57-809320539165 Homework Equations Trigonometry, i.e. sin, cos, tan rules. The 'Z' rule...
  12. Jonski

    How Can the Acceleration of a Crate on a Truck Be Determined?

    Homework Statement At the instant shown, the driver of the truck has just pressed the accelerator pedal down and the truck has suddenly acquired a tangential acceleration of 2.2m/s^2. Coefficient of static friction between crate and tray = 0.4 Coefficient of kinetic friction between crate and...
  13. toboldlygo

    Does pushing down on a book increase the Normal force?

    So, I know that there is a Normal force exerted on the book by the table, and, according to Newton's Third Law, the book exerts a force onto the table. However, I have two questions: if I were to push down on the book, would that Normal force increase? What "creates" the Normal force? Is it the...
  14. Elvis 123456789

    Normal force reading on a scale -- How and why?

    Homework Statement let's say you have a regular bathroom scale, which we know measures the normal force that it exerts on a person aka. apparent weight. Now let's say that we didn't know that it measured the normal force when a object was on it. Obviously we still know that the only two forces...
  15. K

    Why are the normal forces for the legs pointing downwards?

    Homework Statement Hi all! I have been blindly drawing normal forces till today and i stumbled on this question. Homework EquationsThe Attempt at a Solution I have drawn 3 normal forces, - Hand - Leg - Center of mass Is there a normal force at the center of mass and is it the sum of the...
  16. R

    Coefficient of friction - varying normal force

    I'm trying to get my head around the calculation for coefficient of friction: COF = Friction/Normal force. And what happens if you vary normal force. Am I right in saying: The COF is a constant - every pair of materials has a specific COF which is independent of how hard they are pressed...
  17. P

    Calculate Normal Force: Crate & Person on Floor

    Please help with below. is it correct? A 41 kg crate rests on a horizontal floor and a 67kg person is standing on the crate. a. determine the magnitude of the normal force the floor exerts on the crate b. determine the magnitude of the normal force that the crate exerts on the person...
  18. M

    Very confused about normal Force

    I'm having a very hard time understanding the concept of a "Normal Force." The only framework with which I've come to terms with is imagining the Normal Force as the force exerted when object A comes into contact with object B which keeps object B from losing its macroscopic structural...
  19. D

    Frictional Force vs normal force

    Homework Statement A 10 N horizontal force is applied to a 50 N block initially at rest on a rough horizontal surface. If the coefficient of static friction is 0.5 and the coefficient of kinetic friction is 0.4, then the frictional force on the block is A 10 N B 20 N C 0 N D...
  20. L

    Finding what angle is the Normal force is.

    Homework Statement The airplane traveling at a constant speed of 50m/s is executing a horizontal turn. If the plane is banked at ##\theta=15## when the pilot experiences only a normal force on the seat of the plane, determine the radius of curvature of the turn. Also what is the normal force of...
  21. L

    What is the Work Done by Normal Forces in a Children's Slide?

    Homework Statement In a children's park, there is a slide which has a total length of 10 m and a height of 8.0 m . Vertical ladder are provided to reach the top. A boy weighing 200 N climbs up the ladder to the top of the slide and slides down to the ground. The average friction offered by the...
  22. Physkat

    Discrepancy with Normal Force Problems

    As I try to set up equations regarding Newtonian forces, I am looking for patterns in example problems I read. It's really frustrating then when I see different approaches that I can't see a connection to. There are two problems that I've attached that seem to solve - what seems to me about...
  23. S

    Normal force: two boxes with different mass?

    I took a practice Ap Physics test today and did well, but there was a basic problem that hung me up: there are two boxes on the ground on top of each other. the top box's mass is 2m, and the bottom's is 1m. question: just looking at the bottoms box's normal force, does it equal the 2m box on...
  24. G

    Understanding Torque: The Role of Normal Force in Free-Body Diagrams | Explained

    I was just curious as why, when drawing a free-body diagram of a board about a pivot with weight on either side of the pivot, we do not consider the corresponding normal forces to those weights(using torque considerations). This question was already asked in another post but was asked a little...
  25. I

    Resolving in the vertical direction and along the direction of the normal force

    Ok I know this is simple resolving but I'm a bit confused. If we resolve forces in the vertical y direction (as in the attached image), we obtain Rcos(theta)-W=0 and hence Rcos(theta) = W meaning R = W/cos(theta) [where theta = 18 degrees] However, if we resolve forces along the direction of...
  26. gracy

    Case when there is no normal force in spite of contact

    Homework Statement "There is a pulley with 2 blocks on the table.Force "F" is acting on it ,as it can be seen here A=10 kg and B=20 kg F=294 N Now,my exact problem is my teacher says "there is no contact force between A and the table.." Why block A is not pushing against table while block B...
  27. S

    Normal Forces Between Two People on Top of each other

    Homework Statement During an extreme stunt, a 45 kg cheerleader stands on the shoulders of a 55 kg cheerleader, while riding in a transparent elevator with an upward acceleration of 2 m/s2. Find the normal force between the cheerleaders and between the elevator and the bottom cheerleader...
  28. K

    Rolling in a cone, normal force

    I have a small problem with this question. In this problem, the cone exerts a normal force. This force, should be perpendicular to the inside surface of the cone. In equating the vertical forces, I need the vertical component of this normal force. I would draw this force perpendicular to the...
  29. hdp12

    Internal Force Diagram for Rigid Body and Distributed Load

    I'm working on a homework problem for Statics and I'm stuck. Could someone please help?Problem: Draw the internal force (N,V,M) diagrams and include all significant figures Here is all of my work: Resulting F from W1: W(x) = W1 ∴ F2=∫02b W1dx eq (1) ⇒ F2 = W1⋅2b x1 = (F1)-1 ∫02b W1dx =...
  30. RioAlvarado

    Balancing Normal Forces (Statics).

    Homework Statement A horizontal uniform bar of mass 260 kg and length L = 3.0 m is placed on two supports, labeled A and B, located as shown in the diagram. A block of mass 60 kg is placed on the right end of the bar. Find the normal forces FA and FB exerted on the bar by the supports. Enter...
  31. C

    Determining Coefficient of Kinetic Friction w/m, t, and v

    Homework Statement A 2.0 kg block of wood slides over a horizontal surface and comes to rest in 2.5 s. If its initial velocity was 9.0 m/s, what is the coefficient of kinetic friction? Homework Equations rho=mv change in rho=F*change in t Force of friction = mu*Force normal Force normal=mg...
  32. C

    Normal Force While Sliding Off Ice Dome

    Homework Statement Homework EquationsThe Attempt at a Solution I know that the solution involves setting the normal force to zero and equating the radial component of gravity to centripetal force. But why is it not possible for the normal force to decrease at a sufficiently low rate such...
  33. X

    Inclined plane normal force varies by coordinate system?

    Suppose we have a block on an inclined plane. If we choose the x-y axis to be parallel and perpendicular to the inclined plane, then we have Fy = N - mgcos30 = 0 But if we choose our trivial x-y coordinate system, where y is parallel to the force of gravity, then we get: Fy = Ncos30 - mg =...
  34. V

    An object on an incline of 20° (degrees)

    A loaded sled weighing 80N rests on a plane inclined at angle θ= 20° to the horizontal (see pic). Between the sled and the plane, the coefficient of static friction is 0.25, and the coefficient of kinetic friction is 0.15 Taken from...
  35. V

    Normal force cancels out the force of gravity?

    Alright, so I know there will be a normal force pointing perpendicular to the surface and gravitational force, right? Gravitational force = mg But since normal force acts in "opposite direction to the gravitational force". Wouldn't normal force then cancel out the gravitational force? If it's...
  36. leejos16

    Rollercoaster normal force question

    Homework Statement In an amusement park ride called The Roundup, passengers stand inside a 19.0m -diameter rotating ring. After the ring has acquired sufficient speed, it tilts into a vertical plane, as shown in the figure 1. Suppose the ring rotates once every 5.50s . If a rider's mass is...
  37. P

    What is causing the normal force in circular motion?

    In the picture, at point 2 (the bottom of the ramp) the normal force of the object has a greater magnitude than weight. I understand that the normal force has to be greater than the weight since the acceleration points towards the center of the circle and the net force is in the same direction...
  38. S

    Cylinder over a step -- Is the normal force radial?

    Homework Statement [/B] A horizontal force, ##F##, is applied to a cylinder of mass ##M## and radius ##R## (the line of action of ##F## goes through the center) in order for the cylinder to climb over a step of height ##R/2##. 1) Find the torque around ##A## and find force ##F## as a...
  39. terryds

    What Is the Correct Direction of Normal Force in a Stick-in-Well Scenario?

    Homework Statement http://www.sumoware.com/images/temp/xzmbharheaqshjjf.png A homogeneous stick with mass M is placed in a well with smooth surface (see picture). θ is the angle between the stick and the floor. Determine the force the well gives to the stick. Homework Equations ΣF = 0 Στ =...
  40. L

    Normal force of a bead moving around a horizontal ring

    A bead of mass m is threaded on a metal hoop of radius R. There is a coefficient of kinetic friction µk between the bead and the hoop. It is given a push to start it sliding around the hoop with initial speed v0 . The hoop is located on the space station, so you can ignore gravity Find the...
  41. terryds

    Understanding Normal Force Direction in Leaning Ladder & Cable Beam Systems

    I know that normal force is a reaction force. http://www.sumoware.com/images/temp/xzhhpaacgkdktjna.png In the leaning ladder problem, the normal force is perpendicular to the floor and the wall. But, in the cable and beam problem, why isn't the normal force perpendicular to the wall ...
  42. S

    Normal force inside a hollow cone

    Homework Statement A hollow cone is put upside-down with its symmetry axis vertical. The surface of it makes an angle of theta with the vertical direction as shown in the figure . A small puck of mass m slides without friction on the inner side of this cone and remains within a horizontal plane...
  43. I

    Question about frictional and normal force

    Homework Statement Okay so there is a wall that has a mass of 150 kg and I am pushing it but the wall does not move. The coefficient of friction is 2 and I am trying to find the frictional force using the frictional force formula. Although, I need the normal force in which I am using to push...
  44. P

    Does Normal Force change with new Force diagram?

    All degrees are measured from the positive x-axis. FG = Force of gravity FN = Normal force FT = Force of tension Problem: A skier is being pulled up a 15° incline by a rope. I'm solving for FT. The only forces acting on the skier are FG, FN, and FT. Attempt at a solution: Initially, my...
  45. 2

    Force parallel to a smooth wall?

    Hello! My question is quite a quick one- I was wondering whether it is ever possible to have a smooth wall exerting a force parallel to it (and not just perpendicular to it). For example, if you were to place a see-saw by a smooth wall so that the wall is holding one of the see-saw ends below...
  46. S

    Why is Normal Force Negative in this situation?

    Homework Statement The physics of circular motion sets an upper limit to the speed of human walking. (If you need to go faster, your gait changes from a walk to a run.) If you take a few steps and watch what's happening, you'll see that your body pivots in circular motion over your forward foot...
  47. L

    Normal Force at Highest Point of a Rotating Ferris Wheel

    Homework Statement A Ferris wheel has radius 5.0 m and makes one revolution every 8.0 s with uniform rotation. A person who normally weighs 670 N is sitting on one of the benches attached at the rim of the wheel. What is the apparent weight (the normal force exerted on her by the bench) of...
  48. T

    Airplane pilot in a dive, net force, minimum speed, and normal force.

    Homework Statement A 65 kg airplane pilot pulls out of a dive by following at constant speed, the arc of a circle whose radius is 300 m. At the bottom of the circle her speed is 180 km/h. a.) Calculate net force on pilot at bottom or circle. b.) Calculate force exerted on pilot by seat at top...
  49. Shindo

    Boy Holds 100N Sign Against Wall: How Much Push Force?

    Homework Statement If the coefficient of static friction between the sighn and his hands is 0.6, and the coefficient of static friction between the sign and the wall is also 0.6, with what force must the boy push to keep the sign in place? Homework Equations 0.6(Fn)=100 N Fn=166.7 N The...
  50. W

    Normal force on the landing gear when the airplane lands

    Homework Statement An airplane of mass 25,000 kg (approximately the size of a Boeing 737) is coming in for a landing at a speed of 72 m/s. Calculate the normal force on the landing gear when the airplane lands. Hint: You will use 0.92 m as the compression (vertical displacement) of the landing...
Back
Top