What is Block: Definition and 999 Discussions

A block of the periodic table is a set of elements unified by the orbitals their valence electrons or vacancies lie in. The term appears to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-block, p-block, d-block, and f-block.
The block names (s, p, d, and f) are derived from the spectroscopic notation for the value of an electron's azimuthal quantum number: sharp (0), principal (1), diffuse (2), or fundamental (3). Succeeding notations proceed in alphabetical order, as g, h, etc.

View More On Wikipedia.org
Recent contents Top users
  1. Mr Davis 97

    Solving a Simple Diff. Eq: Block in a Frictionless Ring

    Homework Statement This problem involves solving a simple differential equation. A block of mass ##m## slides on a frictionless table. It is constrained to move inside a ring of radius ##l## that is fixed to the table. At t = 0, the block is moving along the inside of the ring (in the...
  2. Mr Davis 97

    Block and acceleration of wedge

    Homework Statement A block rests on a wedge inclined at angle ##\theta##. The coefficient of friction between the block and plane is ##\mu##. The wedge is given a horizontal acceleration ##a##. Assuming that ##\tan \theta > \mu##, find the minimum acceleration from the block to remain on the...
  3. M

    Motion and Forces for a block held against a wall

    Homework Statement Hello, I have attached a physics problem that I solved yet some answers (in red+the first answer) are wrong and I can't find out why... Homework Equations [/B]The Attempt at a Solution [/B]
  4. D

    Length covered by block after collision

    Homework Statement Board ##A## is placed on board ##B## as shown. Both boards slide, without moving w.r.t each other, along a frictionless horizontal surface at a speed of ##6 \text{m/s}##. Board ##B## hits a resulting board ##C##, "head-on". After the collision, board ##B## and ##C## stick...
  5. D

    Why does the Block have an Acceleration Only Downwards

    Homework Statement Block ##A## of mass ##m## is placed over a movable wedge of mass ##m##. Both the block and the wedge are placed over a fixed incline plane. Assuming all the surfaced to be smooth, calculate the displacement of the block ##A## in the ground frame reference in ##1s##...
  6. D

    Condition to not let the block descend

    Homework Statement In the system shown in Fig. ##2E.5 (a)##. block ##m_2## is being prevented from descending by pulling ##m_1## to the right with force ##F##. Assuming all the surfaces to be frictionless, Find ##F## Homework Equations F.B.D of ##m_1## From the F.B.D of ##m_1## we get the...
  7. C

    Solving a Physics Problem: Find Velocity of Block at Bottom of Loop

    Homework Statement This is for my ap physics summer work and is giving me some trouble and could use any help A small block, with a mass of 250 g, starts from restart the top of the apparatus shown above. It then slides without friction down the incline, around the loop then onto the final...
  8. Eclair_de_XII

    Finding static friction of a block on a table on a pulley?

    Homework Statement "When the three blocks in Fig. 6-29 are released from rest, they accelerate with a magnitude of ##0.500 \frac{m}{s^2}##. Block 1 has mass M, Block 2 has mass 2M, and Block 3 has mass 3M. What is the coefficient of static friction between Block 2 and the table?" Homework...
  9. A

    Help adding code block on my blog?

    I was wondering if you guys could help me design (code) a slick code block in my blog like the one here that the reader could scroll? I'm very new to HTML and Java but if I could get just a little help, I would work on it. I really don't have a clue how to add the following to my HTML file but...
  10. T

    Block hanging from cord submerged in water, find density

    Homework Statement A block hangs by a cord from a spring balance and is submerged in a liquid contained in a beaker. The beaker in turn rests on a kitchen scales. The mass of the beaker is 1 kg, the mass of the liquid is 1.5 kg. The spring balance read 2.5 kg and the kitchen scales reads 7.5...
  11. PhysicsClown

    I Do we live in a block universe?

    Experimental violations of Bell's inequality (Alain Aspect, et al) proved beyond a shadow of doubt that local hidden variables do not exist. However, in a 1985 BBC interview, John S. Bell said there was one loophole in those experiments that would allow for determinism: non-local hidden...
  12. H

    Collision and time to stop a block

    [Moderator note: Misplaced homework moved from General Physics, so no template shown] For the part on finding the total time the block spend moving, the answer is ##\frac{v_0}{\mu g}## (attached below). I get a different answer if I use the impulse-momentum theorem: The total change in...
  13. J

    MHB Force on 10 Kg Block on 51° Inclined Plane

    A 10 Kg block lies on a smooth plane inclined at 51 degrees. What force parallel to the incline would prevent the block from slipping?
  14. M

    Difference between node & element & block

    what's difference between node & element & block in analysis software like Ansys?
  15. S

    Floating block with objects that are thrown in a liquid

    Homework Statement I'm confused about the following kind of situation. Consider a block of density ##\rho_b##, mass ##M_b## and section ##S_b## that floats on a liquid of density ##\rho_l##, in a tank of section ##\mathcal{S}##. On the block there are some objects (all equal), of density...
  16. Kloud

    Spring compression after bullet passes through block

    Homework Statement Its in the screenshot i took. I need someone to walk me through the process of solving this problem because I do not understand how to get the maximum compression distance x of the spring. I know that the momentum of the billet will= the momentum of the block. Homework...
  17. L

    Friction problem involving a block and pulley on a ramp....

    Homework Statement In the system, find minimum weight of the block 'B' to start the motion of the block 'A' up the plane.weight of block 'A' 10 KN. The angle of friction for the block and the incline,between the pulley and the string may be assumed as 15° (assume pulley is locked) Homework...
  18. D

    Motion of a block on a steep surface

    Homework Statement The block was given an initial velocity up the surface with an angle of 45 degrees to the ground. Calculate the ##\frac{t_1}{t_2}## with ##t_1## being the time it took to get to the highest point up the hill and ##t_2## the time it took to get down. In both cases the...
  19. JiJiasd

    What distance does the block slide?

    Homework Statement Homework Equations m*v^2 / 2 and k*x^2 / 2 and 0,5*m*v^2 The Attempt at a Solution [/B] in task a I got correct answer there v = 20 m/s in task b I got wrong answer I got the distance = 0,76 m but I should be 32 m here is my answer : 0,5*m*(sin(30)*v) - mu * m*g*cos(30)...
  20. multiplegoats

    The block and spool problem (dynamics of rigid bodies)

    Homework Statement A block and spool are each pulled by a string across a frictionless surface. The string is wound around the spool such that it may unwind as it is pulled, the string attached to the block is at the center of mass. The block and spool have the same mass and the strings...
  21. S

    B Stick-Slip with Chalk: Understanding the Physics

    What is the physics behind drawing dotted lines with chalk with just one stroke? This is a video demonstrating this: Here is what I currently have: as soon as the applied force exceeds that of the frictional, the block will accelerate. What makes it slip though? Because there is a jerk...
  22. Ravi Singh choudhary

    Ice will melt faster which case -- over or below hot block?

    Natural convection always occurs opposite of gravity due to buoyancy; but I am confused as ice is solid so how could possibly convection even contribute to the heat transfer. I doubt about air movements nearby block that may contribute to greater heat transfer rate in case of hot block placed...
  23. A

    Calculate Acceleration, Friction & Speed on 30° Incline | Block Homework

    Homework Statement 3.00-kg block starts from rest at the top of a 30.0° incline and slides a distance of 2.00 m down the incline in 1.50 s. Find (a) the magnitude of the acceler- ation of the block, (b) the coefficient of kinetic friction between block and plane, (c) the friction force acting...
  24. T

    Block Placed on Top of Another Block - Finding Max Force

    Homework Statement [/B] A 0.5kg wooden block is placed on top of a 1.0kg wooden block. The coefficient of static friction between the two blocks is 0.35. The coefficient of kinetic friction between the lower block and the level table is 0.20. What is the maximum horizontal force that can be...
  25. E

    B Which of the two is the reason a block slides down a wedge?

    Is the reason the block slides down the plane that the resultant of the normal force N and mg acts along the plane causing it to slide or is it because of the component of mg parallel to the plane acting on the box i.e. mgsin(theta)
  26. marieb

    How to find the distance the block travels?

    Homework Statement A 15 g bullet is fired at 650 m/s into a 5 kg block that sits at the edge of a 65-cm-high table. The bullet embeds itself in the block and carries it off the table. How far from the point directly below the table's edge does the block land? Homework Equations Impulse=m(delta...
  27. Shawndude

    Rigid block between two cyllinders Ansys apdl

    i want to analyse a two cylinders of different materials between which a rigid block of certain width exists. I am using CE command to connect the nodes of both the cylinders and the constant in Ce equation denotes the width of the the rigid block. When i solve the above problem , stress...
  28. C

    Newtonian Mechanics: Pully/Two Block System

    Homework Statement The blocks of mass 20.0 kg and 10.0 kg are initially at rest on the floor and are connected by a massless string passing over a massless and frictionless pulley. An upward force F is applied to the pulley. Find the accelerations a_A of block A and a_B for block B when F is...
  29. N

    I Is the Block Universe Model Necessary if Presentism Can Adapt to Relativity?

    Is there a scientific difference, if not, why bother with the block universe model given it is unintuitive?
  30. P

    Newton's laws -- Block sliding on a Prism

    Homework Statement All the surfaces shown in fig. are assumed to be frictionless. The block of mass m slides on the prism of mass M which in turn slides backwards on horizontal surface with acceleration of ao. Find the acceleration of smaller block with respect to prism. Homework...
  31. Z

    Solving Block & Spool: Finishing Line & Work-Energy

    Homework Statement A block and a spool are each pulled across a level, frictionless surface by a string. The string wrapped around the spool will unwind as it is pulled. Both the block and the spool have the same mass and are pulled with the same constant tension. Which will cross the finish...
  32. D

    Linear Algebra Book about block matrix multiplication

    I still can't find a book with properties and theorems involving block matrices multiplication to reference in my undergraduate work. thanks
  33. S

    Rotation of a block when not in equilibrium

    Homework Statement Consider a block placed on a surface, in two different configuration, a and b. Explain the condition for which the mass is in equilibrium and describe qualitatively the rotation it follows when it falls. Homework Equations Center of mass theorem \sum F = M a_{cm} The...
  34. Lebombo

    Force and Energy of a block on a spring as it compresses.

    Homework Statement Suppose is a 10kg block sitting at rest on the ledge of a building 20 meters tall. The 10kg block applies a Force of F = ma = 10kg(10m/s^2) = 100N. The potential energy with reference to the ground would then be PE = mgh = 10kg(10m/s^2)(20m) = 2000J. If the 10kg block is...
  35. V

    Position of Final Image in Concave Mirror with Glass Block

    Homework Statement A glass block of thickness 60 cm and refractive index 4/3 is placed in front of a concave mirror. A light source is then placed on the center of curvature of the concave mirror. Find the position of the final image formed. (Focal length is 30 cm) Homework Equations...
  36. Lebombo

    10kg Block free falls from 500ft to 2ft into the ground.

    Hi, may I request help or quick review to ensure that I present an accurate understanding of this concept. I want to move begin learning about the free fall of one block onto another block, but would like to be sure that I understand the physics of work, force, and energy of one block. Thank...
  37. A

    Holding a block of mass in equilibrium on a slope

    Homework Statement A block of mass is held in equilibrium on an incline of angle 30 degrees by the horizontal force 500N. Determine the blocks's weight, ignore friction. Homework Equations F = MA Normal Force y = Fg*sin(theta) Normal Force x = Fg*cos(theta) The Attempt at a Solution I'm...
  38. Eclair_de_XII

    Finding the force to pull a block up a frictionless slope?

    Homework Statement "A 68 kg crate is dragged across a floor by pulling on a rope attached to the crate and inclined 15° above the horizontal. (a) If the coefficient of static friction is 0.50, what minimum force magnitude is required from the rope to start the crate moving? (b) If μk = 0.35...
  39. Eclair_de_XII

    Pushing a block up a slope--how far does it go?

    Homework Statement "A block is projected up a frictionless inclined plane with initial speed v0 = 3.5 m/s. The angle of incline is Φ = 32°. (a) How far up the plane does the block go? (b) How long does it take to get there? (c) What is its speed when it gets back to the bottom?" Homework...
  40. Dave Ritche

    Putting an Image inside of a Div block

    Hello everyone! I designed a webpage and set its main wrapper width to 60% and magin to auto.Inside this wrapper(div),i want to put an image.AS the wrapper-div size is 60%,i put another div inside it and set its width to 100%.The second div(image div) perfectly fit with wrapper-div. I don't know...
  41. x2017

    Work Done on 100 kg Block by 100 N Force in 4s

    Homework Statement A 100 N net force acts on a 100 kg block (initially at rest) for 4s a. How much work was done on the block? (1) b. What is the block’s velocity after the 4 s? (1) c. How much energy does the block have after this time?(1) d. The 100 N net force is no longer acting on the...
  42. A

    How far does the block travel up the incline?

    Homework Statement In the figure, a block of mass m is moving along the horizontal frictionless surface with a speed of 5.70 m/s. If the slope is 11.0° and the coefficient of kinetic friction between the block and the incline is 0.260, how far does the block travel up the incline? Homework...
  43. Elena14

    Solving Pulley Block System Acceleration & Tension

    1. Homework Statement FInd acceleration and tension. Take g=10m/s^2 2. The attempt at a solution By drawing the free body diagrams of every block and simultaneously solving all the equations, I got the answer acceleration= 30/7 m/s^2, which is also correct. But when I try to treat all the...
  44. W

    What is the formula for the weight of a fluid block?

    Homework Statement why the formula of weight of fluid block is given by the formula of ρg[ (R^2) - pi(R^2) ] 1? what does the 1m mean here ? shouldn't it = ρg (pi) (R^2) h ? 2. Homework Equations The Attempt at a Solution
  45. W

    Two-Block Dynamics Problem: Determining Acceleration and Tension

    Homework Statement Assuming no friction is on the plane or the pulleys and the pulley and rope have negligible mass... Determine the acceleration of each block and the tension in each cord. Block A weighs 100kg, Block B weighs 300kg. Homework Equations ΣF = ma ma = 100kg mb = 300kg The...
  46. M

    Block off inclined plane (kinematics + projectile motion?)

    Homework Statement A block of mass m = 2.00 kg is released from rest at h = 0.300 m above the surface of a table, at the top of a θ = 50.0° incline as shown in the figure below. The frictionless incline is fixed on a table of height H = 2.00 m. a. Find a on the incline a=7.51 :) b. Find V(f)...
  47. N

    Concrete Block Incline acceleration question

    Homework Statement A concrete block of mass 25kg is placed on a smooth slope that makes an angle of 30 degrees with the horizontal. Ignoring the effects of air resistance, calculate a) the acceleration of the block as it slides down (g = 9.81 ms-2) b) the distance the block moves in 3 seconds...
  48. jdawg

    Dynamics: Time taken for Block A to slide on Block B

    Homework Statement Find the time it takes for block A to slide 0.5m on block B. Mass A=10 kg Mass B=35 kg I included a screen shot from my online homework. Homework Equations FR=FNμkThe Attempt at a Solution For Block A: mAa=T-FRA-WAsin(30) T=10a+68.67 For Block B: FRC=(mAg+mBg)μBC FRA=mAgμAB...
  49. P

    Faraday cage to block cellphone/Wifi?

    Hi, I was wondering if I could make my house a big Faraday cage capable of blocking Wifi and cellphone signals from the outside by covering all of the inside walls with chicken wire? How big of a problem is it that windows would stay uncovered? Or that electrical wiring inside the wall (so...
  50. SDewan

    Work Energy Theorem in Spring Block System

    Just got confused that while applying the Work - Energy Theorem in a vertical Spring-Block system performing SHM (considering no other external forces other than gravity), when I apply the theorem from equilibrium position, do I consider the work done by gravity?
Back
Top