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. B

    Calculate Normal Force: 55 N Box on Table with 35 N Box and 28 N Hanging Box

    You have a box that wieghs 55 N sitting on a table. On top of that box there is another box that weighs 35 N attached to a frictionless rope that is around a frictionless pully. At the other end of the rope there is another box that is hanging with a weight of 28 N. What is the normal force that...
  2. G

    Normal Force: When is mg not Enough?

    In which cases is the normal force acting on an object simply mg, and in which cases is it something else? If it's not mg, how can I figure out what it is?
  3. A

    Does Normal Force Equal Weight?

    Is the normal force on a body always equal to its weight? YES or NO? I believe the answer is NO.
  4. V

    Find the normal force by each support

    Basically, you have a rod kept horizontally on three supports. It's in equilibrium. The positions of the supports and the mass and length of the rod are given. Find the normal force by each support. The problem looks particularly simple. But notice that you have a shortage of an equation. You...
  5. D

    Calculating Normal Force on Block on Wedge

    A block of mass m is placed on a wedge. The wedge is pushed along a horizontal surface with accelertation a, so that the block stays in place on the wedge, even though there is no friction between the block and the wedge. The normal force acting on the block during the acceleration is equal to...
  6. P

    Why Does a Skier Go Airborne at h=R/3 on a Hemispherical Hill?

    I need help on a physics problem I've been working on... A skier starts at rest at the top of a large hemispherical hill with radius (height) = R. Neglecting friction, show that the skier will leave the hill and become airborne at the distance of h = R/3 below the top of the hill. I...
  7. M

    What is the source of the normal force for a plane flying a loop-the-loop?

    Can anyone provide an explanation as to what the normal force is reacting to in the case when a jet is flying a loop-the-loop?? I understand for a rollercoaster that at the top of the loop the normal force is due to the track exerting a force back on to the rollercoaster cart, contributing to...
  8. T

    Determine normal force and friction of a toboggan with children

    I've tried it but I got stuck at the part to find the coefficient of friction. A parent pulls a toboggan with three children at a constant velocity for 38m along a horizontal trail. The total mass of the children and the toboggan is 66kg. The force the parent exerts is 58N[18 above the...
  9. P

    My weight cancels out the normal force from the floor

    If I'm standing on the ground and at the same time leaning on a wall, what are the forces acting on me? My weight cancels out the normal force from the floor, but what cancels out the force exerted on me by the wall, say horizontally, so as to make the sum of the forces 0? Thanks.
  10. J

    Where is the normal force located on a rollercoaster loop?

    Hi I have to draw a freebody diagram for FN (normal force) of an object at different locations on my rollercoaster. Where would FN be located when the object is upside down (going through a loop) ... would it just be straight down? (like gravity) ? Because FN is always perpendicular to the...
  11. S

    Calculate Normal Force Exerted on Hands During Push-Ups

    Not quite sure what to do about this one: -----A person whose weight is W = 601N is doing push-ups. Assume L1 = 0.859m and L2 = 0.353m. Calculate the normal force exerted by the floor on each hand, assuming that the person holds this position. ------ I can't get the picture on here, but...
  12. S

    When to Use Conservation of Energy and Work Energy Theorem

    A small mass m slides without friction along the looped apparatus. If the mass is to remain on the track at all times, even at the top of the loop of radius r. If the release height is 2h, calculate the normal force a. exerted by the the track at the bottom of the loop. 11mg...
  13. J

    What Angle and Normal Force Are Involved When Pulling a Suitcase?

    This may be very simple... but here is the question. This is the question.. A woman at an airport is towing her 20.0 kg suitcase at constant speed by pulling on a strap at an angle of (theta) above the horizontal. She pulls on the strap with a 35.0 N force, and the friction force on the...
  14. L

    Determine the magnitude of the normal force exerted by the table.

    hi, i need some help w/ this problem: a) A block of mass 2.00 kg is pushed 2.32 m along a frictionless horizontal table by a constant 17.7 N force directed 25.5 degbelow the horizontal. Determine the work done by the applied force. b) Determine the magnitude of the normal force exerted...
  15. P

    What is the minimum normal force he must exert?

    The 50.0 kg climber is supported in the "chimney" by the friction forces exerted on his shoes and back. The static coefficients of friction between his shoes and the wall, and between his back and the wall, are 0.90 and 0.65, respectively. What is the minimum normal force he must exert? Assume...
  16. G

    Normal force on box on elevator floor?

    In Fig. 5-42, elevator cabs A and B are connected by a short cable and can be pulled upward or lowered by the cable above cab A. Cab A has mass 1700 kg and cab B has mass 1200 kg. A 12.0 kg box of sand lies on the floor of cab A. The tension in the cable connecting the cabs is 1.86 x 10^4 N...
  17. L

    Solve a Physics Problem: Normal Force Calculation for a 38.0kg and 17.0kg Box

    A 38.0 kg box (m1) rests on a table. A 17.0 kg box (m2) is placed on top of the 38.0 kg box. What is the normal force that the 38.0 kg box exerts on the 17.0 kg box. I found that the normal force of just the 38.0kg box is 372.78N and the normal force of just the 17.0kg box is 166.77N. But I...
  18. B

    Normal force calculation

    if the normal force defined as the force that acts on an object when it touches the surface perpendicularly, wouldn't it be at the opposite direction of the Weight (W) as a vector and with the same absolute value.. so that the formula would be : F(n)= -mg if this formula is correct (which is...
  19. Q

    Increased normal force due to rotation

    I am studying for my graduate exam in physics and came across a strange phenomenon and I would like to make sure I am reasoning it correctly: Start with a hemispherical bowl and place a small sphere (relatively) at the edge. Let the sphere roll towards the center of the bowl, thus gaining...
  20. H

    Calculate the normal force and the tension in the string

    Hello. I am starting tension in my physics class and am stuck on a problem. I was wondering if anyone could help me out. It seems really simple: an object of mass 50kg is being held by a string attached to the top of a frictionless inclined plane that is 60 degrees above the horizontal. I...
  21. S

    Tension in the string and the normal force exerted by the wall

    A uniform solid disk of mass M and radius R hangs from a string of length l attached to a smooth wall. We want the tension in the string and the normal force exerted by the wall. | |\ <--- I call this angle A |_\ |__\ |_(..) <--- that's a disk | | So I have it set up so the...
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