Normal force Definition and 471 Threads

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.

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  1. A

    Normal force in circular motion

    Hi, Suppose we have a fellow on a ferris wheel. Would the normal force be greater on the top or at the bottom of the ferris wheel? I'm thinking that it would be greater at the top, or am I wrong? Thanks,
  2. P

    Question about a magnet and normal force.

    Lets assume that liquid superconductors exist. Now I place a magnet above a pool of the liquid. Now will the surface of the liquid remain level or will it appear to have dent in it. I am not sure I kind of back and forth in my head.
  3. M

    Normal force in man-on-ladder torque questions?

    Homework Statement This is just a more generalized question, and not really about a specific value. The question was regarding torque, and had a man standing on a ladder like so. The only force (exerted by the man on the ladder) that provided torque was indicated to be mg, but I don’t really...
  4. F

    Bike/motorcycle leaning in a curve. What happens to the normal force N?

    Hello Forum, If a bike is negotiation a curve, the static friction force will supply the centripetal force F_c. If we go too fast and the friction is not enough we skid along the tangent. There are two forces: the weight W=mg pointing down, the normal (contact) force N pointing up and...
  5. S

    Friction and normal force on an incline

    I have an incline A that is very steep reaching a vertical height of h and another one B which is less steep with the same vertical height. So using the work energy theorem: in A, KE+work done against friction=mgh so the work done against friction and initial KE is equal to the gain in...
  6. T

    Inclined planes, Banked highways, and Normal force

    Alright, I don't have a specific homework problem here, just a general question. I've attached two pages that I will be referencing. Figure 1. Inclined Plane As can be seen here, the FN = mgcos(∅) Figure 2. Banked Curve It seems as if the opposite is true here. FNcos(∅) = mg...
  7. mishima

    2 explanations for normal force

    I have heard 2 informal explanations for the normal force during a situation like a book resting on a table: 1. The springiness of the atomic lattice in the table attempts to restore its original structure, thus pushing the book. 2. Since there are electrons on the outside of both the...
  8. Q

    What Is the Normal Force on a Sliding Ladder?

    Homework Statement A ladder of length l and mass m leans against the side of a house, making an angle θ with the vertical. Assume that the ladder is free to slide at the point where it touches the side of the house (there is no significant friction). Find an expression for the normal force...
  9. I

    Mechanism that causes tension and normal force?

    Homework Statement What is a mechanism that might cause a rubber band or a string to develop tension in response to a force that you apply? What mechanism explains how walls and tables exert normal forces without bending noticeably? Homework Equations None, since this is a...
  10. F

    Why should you feel lighter at equator if normal force is weaker?

    Ok forgetting everything about how Earth is not a perfect sphere, the greatest centripetal acceleration is at the equator. So if you say N - Mg = -Mac, N should equal M(g-ac) which gives a weaker force than the gravitational force. If the net force is a force towards the center of earth...
  11. D

    Easy but hard problem (loop-the-loop) normal force?

    Homework Statement The Gravitron single-car roller coaster consists of a single loop-the-loop. The car is initially pushed, giving it just the right mechanical energy so the riders on the coaster will feel "weightless" when they pass through the top of the circular arc. How heavy will they...
  12. P

    Normal Force during centripetal acceleration

    General Question Here: Let's say you are swinging a ball around on a string. Will there be a normal force?
  13. R

    Block on a ramp Sum of forces, normal force, static friction, etc Question

    Ok so I already know how to solve it by looking at an example my teacher did in class... This is what I did... 4. A 2.00 kg block is held in equilibrium on an incline of angle θ = 70° by a horizontal force vector F applied in the direction shown in the figure below. If the coefficient of static...
  14. D

    Normal Force of an object being pushed

    You push a 8.00 kg suitcase across a smooth horizontal floor applying a force directed 35.4 degrees below the horizontal. Someone measures the acceleration of the suitcase to be 1.26 m/s2. Assuming g = 10.0 m/s2, what is the normal force the ground exerts on the suitcase? So is normal...
  15. D

    Magnitude of normal force from ceiling to man

    Homework Statement tall strongman of mass m = 93 kg stands upon a scale while at the same time pushing on the ceiling in a small room.If the scale reads 1062 N (about 239 lb), what is the magnitude of the normal force that the ceiling exerts on the strongman? Homework Equations N=m...
  16. D

    Solving for Normal Force between two objects

    Homework Statement Your friend's car broke down. You push it to a repair shop 2.0 km away. You gently put your car's bumper against the broken car's bumper and accelerate to a speed of 2.5 m/s over the course of 1 min. If the broken car's mass is 1200 kg, what is the normal force between the...
  17. J

    Statics Equilibrium: Normal Force and Static Friction

    1. The homogeneous square body is positioned as shown. If the coefficient of static friction at B is 0.40, determine the critical value of the angle theta below which slipping will occur. Neglect friction at A. The image: 2. NA is the Normal force at A, which is perpindicular to the...
  18. J

    Why is there no action-reaction pair for normal force?

    Here is an example in which the normal force would not be counted as an action-reaction pair. A 100g block is sitting at rest on a horizontal table. According to Newton's third law, which of the following indicates the correct action-reaction pair of the two forces? So I was stuck between C. The...
  19. S

    Normal force of weight on the ground

    Homework Statement If we are simply standing on the ground will our normal force be always equal to our weight besides when we are jumping or when we land on the ground from a fall? When we are in an elevator, will the normal downwards force on the floor be of our weight (cancelling out our...
  20. I

    Need help in determining normal force the question is from ss krotov

    cylinder of mass m and radius r rests on two supports of same height. one is fixed other slides with velocity v.determine normal force N by the cylinder on stationary support at the moment when distance between the point of contacts A and B of cylinder and support) is r√2assuming supports were...
  21. R

    How Do You Calculate the Acceleration of Buckets Using Tension and Mass?

    Two buckets of nails are hung one above the other and are pulled up to a roof by a rope. Each bucket has a mass of 5.0kg. The tension in the rope connecting the buckets is 60 N. Calculate the acceleration of the buckets. So here's what I did: mt= ma + mb (m which is equal to mass) mt=...
  22. R

    The Slope of a Normal Force vs Applied Force Graph

    Homework Statement An experiment was conducted where a slider with different mass combination is placed on a board. A Newton spring scale is attached to the slider and is pulled horizontally and parallel to the board such that the slider moves at a constant velocity. The applied force...
  23. L

    Frictional force, normal force and coefficient of friction

    Homework Statement Calculate the frictional force, normal force and coefficient of friction for an 0.2kg object that is lying on a 35 degree incline. Homework Equations Ff= u x Fn F= m x a The Attempt at a Solution I managed to get FN= m x a x cos# = -9.81 x 0.2 x cos35 = 1.61...
  24. B

    Whats normal force at top/bottom of loop

    Homework Statement The small mass m sliding without friction along the looped track shown in the figure is to remain on the track at all times, even at the very top of the loop of radius r. http://session.masteringphysics.com/problemAsset/1057653/6/GIANCOLI.ch08.p090.jpg A)In terms of...
  25. A

    What Is the Maximum Speed a Car Can Travel Without Skidding on a Circular Track?

    Physics lab normal force please help! A 1000-kg car moves at a maximum speed so that it does not skid off the 50-m radius level track. If the coefficient of static friction between the road and wheels is 0.80. What is the maximum speed? Assume that the gravitational constant is 10.0 N/kg =10.0...
  26. P

    Weight in an Elevator and Normal Force

    Homework Statement A person who normally weighs 200 lbs is standing on a scale inside of an elevator. The elevator is moving downwards at a constant speed of 7.0 m/s and then begins to slow down at a rate of 4.9 m/s^2. Before the elevator begins to decelerate, the reading of the scale is...
  27. J

    Need help calculating friction and normal force for Measuring Friction Lab

    Need help calculating friction and normal force for "Measuring Friction" Lab Hey guys, I'm not great at physics and have a lot of work ahead of me so I could use some help. The lab setup is a wooden block sliding on a wooden surface. There is a weight attached to the block by a string that's...
  28. A

    Normal force always point perpendicular to the plane?

    Why is it that the normal force always point perpendicular to the plane? If I imagine the ground as made up of a bunch of particles I find it hard to see, why they should necessarily direct their forces perpendicular to the plane. Consider as a classical example a box sliding down a slope. The...
  29. A

    Adding Normal Forces for Net Force Calculation

    Homework Statement How do you add the normal forces together after you derive the x and y component? Homework Equations Normal force = m*g*sinθ (y component) Normal force = m*g *cosθ (x- component) The Attempt at a Solution Bottom line is I'm trying to get the Net Force...
  30. P

    Is the Normal Force Always Equal to the Weight of an Object?

    Which is true/false? When a force is called a "normal force", it is: A force that is always equal to the weight of the object. A force that is perpendicular to the surface of the Earth at any given location. A contact force perpendicular to the contact surface between two solid objects...
  31. C

    Why Is Normal Force Less Than mg at the Top of a Hill?

    So in class today we were talking about Normal Force, and I was really confused on one diagram. Here is a link about the question, but I don't understand why n<mg because if it is less than mg wouldn't that make it go through the earth? not sure but help understanding would be great...
  32. L

    Normal force on top of a loop?

    Say we have a roller coaster, and we want to calculate the speed the roller coaster can go at barely making the loop. Normally, the equation would be n+w=m*v^2/r, but why do we set normal equal to zero when we're solving for the minimum speed? Where does the normal come from on top of the roller...
  33. S

    Question about friction and normal force

    Homework Statement A 3.5 kg block is pushed along a horizontal floor by a force F of magnitude 15 N at an angle of 40 degrees DOWNWARD. The coefficient of kinetic friction between the block and the floor is 0.25. My question is about the normal force. I know the normal force is given by...
  34. S

    Kinetic Friction, Undefined Pushing Force, Find Normal Force.

    Homework Statement A crate is pushed at constant velocity across a rough, horizontal surface by a push force P. The crate has a weight of 73N. Coefficient of kinetic friction between the crate and the floor is 0.41. Vector force P points at an angle of 37 degrees below the horizontal. What...
  35. B

    Find torque in disc brakes given normal force and coefficient of friction

    Homework Statement In the disc brakes that slow down a car, a pair of brake pads squeezes a spinning rotor; friction between the pads and the rotor provides the torque that slows down the car. If the normal force that each pad exerts on a rotor is 85 N, and the coefficient of friction is 0.62...
  36. D

    Find the normal force on an inclined plane.

    Homework Statement Find the normal force acting on a mass of 5kg on an incline plane of 30 degrees. Homework Equations Fn = mgsin30 or mgcos30 ? The Attempt at a Solution I'm not sure if I use sin or cos when finding the normal force on an incline. I have trouble visualizing the...
  37. L

    How Do You Calculate Normal Force and Tension Direction at Point O?

    2. Homework Equations : N=mg; M=Fl 3. The Attempt at a Solution : i find that the normal force of the rope AD is 8.5N. Hello. Sorry that in my first post I'm already asking for help, but I'm getting really desperate with this problem. I need to find the Normal force at the point O and direction...
  38. P

    Solving Normal Force Problem: Find Fn with Ks=46.0 J, v=4.50m/s

    Homework Statement A block is sent up a frictionless ramp along which an x-axis extends upward. The figure below gives the kinetic energy of the block as a function of position x; the scale of the figure's vertical axis is set by Ks = 46.0 J. If the block's initial speed is 4.50 m/s, what is...
  39. M

    Calculating weight of underwater object given normal force

    Homework Statement A glass ball of radius 2 cm sits at the bottom of a container of milk that has a density of 1.03 g/cm^3. THe normal force on the ball from the container's lower surface has a magnitude of 9.48 * 10^-2 N. What is the mass of the ball? Homework Equations Normal force +...
  40. V

    What is the Normal Force on a Rider in a Ferris Wheel at the Midpoint?

    Homework Statement The original problem is Figure P6.61 shows a Ferris wheel( I have attached the image) that rotates four times each minute. It carries each car around a circle of diameter 18.0 m. (a) What is the centripetal acceleration of a rider? What force does the seat exert on a...
  41. V

    Conflict normal force in inclined plane

    Homework Statement The original problem was as follows: A civil engineer wishes to redesign a curved roadway in such a way that a car will not have to rely on friction to round the curve without skidding. In other words, a car moving at the designated speed can negotiate the curve even when...
  42. S

    How Do You Calculate Normal Force for a Cup and Saucer on a Table?

    [b]1. A cup and saucer rest on a table top. The cup has mass of 0.176 kg and the saucer 0.165 kg. Calculate the magnitude of the normal force a). the saucer exerts on the cup and b). the table exerts on the saucer. Too be honest I really don't know the equation. I think it might be...
  43. I

    Scale Reading of Normal Force: Due by Midnight

    Remember that a scale records the value of the normal force, not a person’s actual weight. Draw a FBD. Rotate your coordinate system. A 61 kg student weighs himself by standing on a scale mounted on a skateboard that is rolling down an incline, as shown. Assume there is no friction so...
  44. S

    Finding normal force acting on an object (Fn)?

    [b]1. A couch with a mass of 100 kg is placed on an adjustable ramp connected to a truck.If the couch slides down the ramp with an acceleration of 0.8 m/s^2: [b]2. find the normal force on the couch [b]3. my way: Fg=m*9.81=981 Fnety=0N 981 sin 270+f sin 180+Fn sin 90=0N -981Fn=0...
  45. R

    Finding the Relationship between Static Friction and Normal Force

    Homework Statement So I have this lab I have to do about finding the relationship between static friction and normal force. So basically I need to find find how the Static Friction and Normal Force relate by doing a lab experiment. The materials I have are: Spring balance / scale Weights...
  46. M

    Statics 2D Virtual Work problem regarding calculation of Normal force

    PROBLEM 1 Homework Statement The frame in the figure is supported by a hinge in A and a roller in G. It is loaded by a couple = 14 kN*m in B, a force = 12 kN in D and a distributed force = 4 kN/m on section EG. = 1.4 m. Calculate the normal force in C. Use the correct signs...
  47. S

    Is Any Applied Force Truly a Normal Force?

    THIS IS THE QUESTION: Your teacher says, “Any applied force can also be called a normal force.” Discuss the validity of this statement. Thanks guys.
  48. T

    Finding the Normal Force of a block on an incline experiencing centripetal force

    Homework Statement When the sliding along a horizontal circular path on the inside of a friction-free cone, the magnitude of the normal force (use the diagram) 1. is greater than mg, always. 2. is equal to mg. 3. may be greater than mg. 4. is less than mg, always. 5. may be less than...
  49. T

    Finding the Normal Force of a block

    Homework Statement And when the block is sliding along a horizontal circular path on the inside of a friction-free cone,the magnitude of the normal force (use the diagram) 1. is greater than mg, always. 2. is equal to mg. 3. may be greater than mg. 4. is less than mg, always. 5. may be...
  50. S

    Finding normal force of moving crates

    Homework Statement Your moving company runs out of rope and hand trucks, so you are forced to push two crates along the floor as shown in the figure below. The crates are moving at constant velocity, their masses are m1 = 49 kg and m2 = 29 kg, and the coefficients of kinetic friction between...
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