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.

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  1. L

    Status of the block universe in the field of physics

    Hi. I did a quick search for threads on the block universe and came across one about the implications of the block universe. That was closed though because it was too philosophical. I don't really want to know about the implications of the block universe, I'm just wondering how physicsts...
  2. K

    Where a block stops on a loop-the-loop

    Homework Statement A small block of mass m slides along a frictionless loop-the-loop track. The block is released from rest at point P. What is the resultant force acting on it at point Q? At what height above the bottom of the loop should the block be released so that it is on the verge of...
  3. K

    Calculating Volume of Water Displaced by 12 kg Wooden Block

    A 12 kg wooden block is floating in a swimming pool. The density of the wood is 600 kg/m3. How many cubic meters of water does the block displace? (a) 0.044 (b) 0.066 (c) 0.012 (d) not enough information to answer (e) none of these I'm really confused on this concept. I know that the...
  4. K

    A 1.2 kg block is pushed under water and held there. What is the buoyant force?

    A 1.2 kg block is pushed beneath the water and held there. What is the buoyant force (in N) acting on the block? (a) not enough information to answer (b) 11.76 (c) 1.2 (d) 14.56 (e) none of these Since buoyant force is equal to the wt of the water displaced, I used the equation w=mg...
  5. U

    Force of block pushed against wall

    Homework Statement A block of mass 20 kg is pushed against a vertical surface (see picture). The coefficient of friction, μ, between the surface and the block is 0.2. If θ = 30°, what is the minimum magnitude of P to hold the block still? Homework Equations f = force of friction = μN...
  6. L

    Two block system with friction

    Two blocks connected by a rope of negligible mass are being dragged by a horizontal force F. Suppose that F=68 , m1=12kg, m2=18kg, and the coefficient of kinetic friction between each block and the surface is 0.100. Determine the tension, T, and the magnitude of the acceleration on the system...
  7. R

    Acceleration of a Block on an Inclined Plane

    7. A block of mass m = 5.5 kg is pulled up a θ = 22° incline as in the figure with a force of magnitude F = 38 N. (a) Find the acceleration of the block if the incline is frictionless So I got this one right, and here is what I did... From the free body diagram I drew: Fnet = (38...
  8. 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...
  9. P

    Solving for Mass of Block of Ice w/ Newton's 2nd Law

    Homework Statement A dockworker applies a constant horizontal force of 80 N to a block of ice on a smooth horizontal floor. The fritional force is negligible. The block starts from rest and moves 11 meter in 5 seconds. What is the mass of the block of ice? Homework Equations Newton's...
  10. O

    How Does Incline Angle Affect Ice Block Acceleration on a Frictionless Ramp?

    A block of ice of mass m is released from rest at the top of a frictionless ramp of length L. at the bottom of the incline the speed of the ice is v1. given m,L,v1 determine the time needed to hit the bottom the angle between the ramp and the horizontal the accel of the ice I made my...
  11. A

    Finding the possible values of a force pushing a block

    Homework Statement Homework Equations I believe the only necessary equations would be those utilized to find the X and Y components of a certain force as well as the formula used to find μs µ = ffriction/fnormal The Attempt at a Solution Attempt: I'm not really sure where...
  12. F

    Minimum force needed to move block

    This isn't a specific problem, but it is a concept that appears in several problems. I'll give an example problem that should make clear what I mean. A block rests on a horizontal surface. Ffric≤1 N. What force (applied horizontally) is needed to move the block? My physics professor...
  13. F

    Force required to keep block from sliding down (check)

    Homework Statement The two blocks (with m=16kg and M=88kg) shown in Fig. 6-56 are not attached. The coefficient of static friction between the blocks is \mustat=0.38, but the surface beneath the larger block is frictionless. what is the minimum magnitude of the horizontal force \vec{F}...
  14. H

    A block with mass on a wedge with mass.

    Homework Statement The surfaces between a 9 kg block, the 15 kg wedge and between the 15 kg wedge and the horizontal plane are smooth (without friction). The acceleration of gravity is 9.8 m/s. A block is released on the inclined plane (top side of the wedge). What is the force F...
  15. J

    So why does the atmosphere block gamma rays but not UV rays?

    Or light rays for that matter. Where does the window open in the atmosphere on the em spectrum, UV? Why is that?
  16. O

    How Is Acceleration Calculated for a Block on a Frictionless Surface?

    Homework Statement A block of mass 6.7 kg is pulled along a horizontal frictionless floor by a cord that exerts a force of 56.0 N at an angle 27.9o above the horizontal. What is the magnitude of the acceleration of the block? Homework Equations f=ma The Attempt at a Solution i split...
  17. T

    Block held by a rope on an incline

    Homework Statement A block with mass m1 = 9.4 kg is on an incline with an angle θ = 31.0° with respect to the horizontal. There is also a massless rope that pulls horizontally to prevent the block from moving. What is the tension in the rope? Homework Equations Fg = m*g Fg,x = m*g*sin...
  18. F

    How to find the volume of a block that weighs 107 Newtons.

    Just a problem for my physics homework and just wondering how to solve this problem.
  19. T

    Block moving on a circular track-Work energy Circular Motion problem

    Homework Statement A block of mass 1 Kg initially at rest at point B is being pulled by a constant force F= 100N along a smooth circular track of radius 10 m . Find the velocity of the block when it reaches point P making an angle 60 with the vertical. Homework Equations The Attempt at a...
  20. A

    Young's double slit experiment with one slit covered with block of refractive index

    Homework Statement The interference pattern formed is given by I(θ)=4I0cos2(∏dsin(θ)/λ). For d=1×10-5m and λ=500nm plot the intensity pattern as a function of θ for small θ. How would this change if a block of material of thickness 500nm and refractive index n=1.5 were placed over one slit...
  21. M

    Mathematica How to put a matrix in its block diagonal form (Mathematica)

    Hello. I got a 10x10 matrix that I know that has a block diagonal form. How can I put it in that form, using Mathematica? Regards, Marcus.
  22. N

    Block moving up an incline with friction

    Homework Statement A block of mass m is moving along a horizontal frictionless surface with a speed of 5.7 m/s. The block encounters a slope which it travels up. If the slope is 11 degrees and the coefficient of kinetic friction between the block and the incline is 0.26, how far does the block...
  23. dexterdev

    Why sine wave is the basic building block signal to make other signals?

    Why sine wave is the basic building block signal to make other signals? Not any other wave. -Devanand T
  24. A

    Finding the resultant force on the block

    Homework Statement Hi all, I've been given a question for homework and I am not 100% sure how to do it exactly! I have included a diagram or the situation Homework Equations The question is Find the resultant force on the block (picture attached) The Attempt at a Solution What i did...
  25. H

    Find force to push block up incline with static and kinetic friction in certain time

    pHomework Statement A 5.03 box sits at rest at the bottom of a ramp that is 8.76 long and that is inclined at 30.0 above the horizontal. The coefficient of kinetic friction is 0.40, and the coefficient of static friction is 0.50. What constant force , applied parallel to the surface of the...
  26. K

    [Math Verification] Massless Pulley - Acceleration of Block A & B?

    Homework Statement http://img152.imageshack.us/img152/8286/imag0103l.jpg *I'm aware my free body diagram is off and that normal force should be in the left quadrant. Homework Equations F=m*aThe Attempt at a Solution Would I be correct in saying.. Fg of A = mg * sin (20) = 2kg * 9.8 * sin...
  27. Y

    Bullet shot through stationary wooden block

    Homework Statement So I have a block that has had a bullet shot through it at an initial speed of 280m/s. It is 0.03kg and after it leaves the block it is traveling at 190m/s. The block is a length of 0.012m and weighs 1.50kg. What is the average force exerted on the block? Homework...
  28. D

    Solving Block B's Stop Time: A 1-lb Ball & 10-lb Block

    Homework Statement A 1-lb ball A is traveling horizontally at 20 ft/s when it strikes a 10-lb block B that is at rest. If the coefficient of restitution between A and B is e = 0.6, and the coefficient of kinetic friction between the plane and the block is µk = 0.4, determine the time for the...
  29. A

    Bullet hits a block, penetration depth and velocity

    Homework Statement A bullet with mass and speed v hits a wooden block of mass M that is situated at rest on a frictionless surface. It penetrates the block and gets trapped inside it as a result of a constant retardation force F_{ret} that opposes relative motion between the two objects...
  30. M

    Simulink USS block - probability analysis

    Here are the basics - I've got a model with a computed distance between 2 objects. The likelihood that object A will detect object B is a probability dependent on distance (and its a cumulative lognormal curve). I want to include a probability function based on that computed distance. So that...
  31. S

    Mass of a block floating over a heterogeneous density bar

    Hi! I just wanted to ask something. If i have a block, that is resting on the left side of a bar, and everything is floating on water, how can I calculate the mass (m) of that block? (I have the mass of the bar (M) and the volume on the block (V))
  32. T

    Find velocity of hanging block in a pulley system

    A pulley is set up on the edge of a desk. A light string connects a 10 kg block laying on the desk to a 4 kg block hanging off the pulley. The only significant friction is with the desk, and the coefficient of kinetic friction is 0.20. Use the law of conservation of energy to find the speed of...
  33. T

    Block sliding up an inclined plane lab

    Homework Statement A block is given an initial speed of 3m/s up a 22° inclined plane. How far up the plane will it go? How much time elapses before it returns to its starting point? Homework Equations D = 1/2at2 a = Δv/t Vf2 = Vi2+ 2a*d The Attempt at a Solution The Vy is 1.12m/s...
  34. E

    Block form of the generators of the fundamental representation of SU(2N)

    Homework Statement I am calculating the corrections to the beta functions of a quite general SU(N) gauge-yukawa theory coming from coupling an electro-weak (SU(2)xU(1)) sector similar to that of the Standard Model. To do this, I need to calculate...
  35. N

    Block Acceleration up an Inclined Plane

    Homework Statement A cable is pulling a 200kg block up an inclined plane elevated at 30 degrees with 3.5KN of force. How fast is the block accelerating at? θ = 30 g = 9.81 m = 200kg μ = 0.35 F = kN Homework Equations F = ma The Attempt at a Solution Wasn't sure how to do this problem, I...
  36. W

    (Find time it takes a block to travel) Dynamics

    Homework Statement How long would it take for the block to travel 10m starting from zero velocity? (i.e. T =?) (Look the the attached picture for the block and the position of it on the plane at 45 degree and 10 m from ground with the same slope) Theta = 45 degrees m = 1.0 kg f = 0.3...
  37. B

    What is the acceleration of a block in this scenario?

    Homework Statement Okay, i am preparing for an exam so the questions i am doing are only for my learining they will not be marked anyway I already know that the answer is C) 0.5ms-2 what i need is an explanation, i don't understand how that answer was derived... I thought it would...
  38. D

    Cubical block on a cylinder challenging problem

    Homework Statement A cubical block of side L rests on a fixed cylindrical drum of radius R. Find the largest value of L for which the block is stable. This is problem 6.35 from the Kleppner+Kolenkow Introduction to Mechanics book. I honestly have no clue where to even start on this problem...
  39. M

    Fluid Mechanics - find a cavity of a block if it exist?

    Homework Statement You are given a 10cm Cube of aluminum with Density of 2700kg/m is submerged in water and the weight in water is 13N. If a cavity exist how big is it? Homework Equations The equation i used were B = V * P_water * g to find buoyancy. To find the enclosed cavities i...
  40. L

    Discover the Angle of Swing: Solving for the Motion of a Bullet and Block System

    Homework Statement : A bullet of mass 25g is fired at 425m/s into a block of wood , mass 1.200kg,hanging at the end of a 1.0m long string which is attached to the ceiling .The bullet becomes embedded in the block causing it to swing back along an arc.Through what angle does the block swing...
  41. J

    Simple block kinematics problem

    Homework Statement Block A weighs 75lbf and the coefficients of static and kinematic friction between A and the plane are both 0.50. Determine the acceleration of A under the action of the 25 lbf force when the velocity at A is (a) 8fps up the plane, (b) 15 fps down the plane. (c) Zero...
  42. R

    Simplify Block Diagrams: Finding Overall Transfer Equation for Homework

    Homework Statement finding the overall transfer equation Homework Equations not sure which equation to use The Attempt at a Solution unsure how to solve this, don't know where to start off from
  43. O

    Refraction - A light ray is incedent on a block of glass at an angle of 30 degrees

    Refraction -- A light ray is incedent on a block of glass at an angle of 30 degrees Homework Statement A light ray is incedent on a block of glass at an angle of 30 degrees,what is the angle of refraction. Given: glass: 1.47 incident angle:30° Homework Equations π1 sin θ1 = π2 sin...
  44. S

    How to display a real time graph in the Matlab GUI from simulink block

    I want to display a real time signal from ECG I use simulink block -scope and want it to be display in gui axes This is a code from some other guy function Command1_Callback(hObject, eventdata, handles) button_state = get(hObject,'Value'); if...
  45. E

    Eigenvalue of overlapping block matrix

    I have got a problem in my research. For the following matrix, a a a a a a b b b b a a a a a a b b b b a a a a a a b b b b a a a a a a b b b b a a a a a a a a a a a a a a a a a a a a b b b b a a a a a a b b b b a a a a a a b b b b a a a a a a b b b b a a a a a a, does anyone know how...
  46. A

    Block moving around in a semi cricle

    Homework Statement A cylinder is cut out of a large block with mass M=4kg sitting on a table. A small block of negligible size and mass m=0.5kg is placed within the hole. All the surfaces are frictionless. The radius of the cut is R=0.80m and the angle is 25 degrees. Basically there's a...
  47. S

    Force required to tip block backwards

    Homework Statement There is a 2-D block with height H, width W, and mass M. (H > W) A force F is applied from behind the block at a height 0.1H from the ground. If the coefficient of friction is μ, what does the force F need to be to cause the block to tip backwards? Homework Equations...
  48. S

    Bullet Hits Block Attached to Spring What am I doing wrong?

    A wooden block of mass M = 1.83 kg is rest on a frictionless, horizontal table attached to the end of an unstretched spring (k = 217 N/m). A bullet of mass m = 8.02 g is fired horizontally into the block at speed vo = 394 m/s. The bullet comes to rest inside the block, and causes the mass to...
  49. K

    Block attached to spring is kicked,what distance will the spring stretch?

    A block, no friction, of 1 kg is attached to a spring rests on a horizontal surface with a length L. The spring is connected to a fixed point. The 1kg block is kicked and has a velocity of 1 m/s. As the block swings around the fixed point, the spring stretches to a total distance of L + x, at...
  50. L

    Help finding friction force of block moving across horizontal atwood's machine

    Basically we did a lab where you attach a pulley to the desk with a clamp and then have a friction block (three types: cork, plastic, and felt) attached to a string which is attached to a hanging mass. This basic setup is called an atwood's machine. The purpose of the lab was to identify the...
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