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. D

    Adding mass when a blocks rests on another block?

    Homework Statement The figure shows a 1.0 kg mass riding on top of a 5.0 kg mass which is attached to a spring. The 5.0 kg mass oscillates on a frictionless surface, and the spring constant is k = 50 N/m. There is friction between the upper block and the lower block, and the coefficient of...
  2. M

    Finding the speed of the block for one and two springs

    Homework Statement The spring in the figure (Figure 1) is compressed by length Δx. It launches the block across a frictionless surface with speed v0. The two springs in the figure (Figure 2) are identical to the spring of figure 1. They are compressed by the same length Δx and used to launch...
  3. E

    What Is the Coefficient of Kinetic Friction for a Block on an Inclined Plane?

    Homework Statement A block with a mass of 820 g starts from rest at the top of an inclined plane that is 106 cm long and makes an angle of 49.5 degrees with the horizontal. It accelerates uniformly down the ramp and reaches the bottom in 0.89 s. What is the coefficient of kinetic friction on...
  4. Wrichik Basu

    B Why are only some parts of this ice block cloudy?

    I had a sprain in my leg a few days back. The doctor recommended dipping my foot alternately in ice-cold and hot water to aid blood circulation. It is here that I discovered something interesting. The picture above shows the piece of ice that was put in the bucket. The above picture shows...
  5. C

    Conservation of Energy: Spring pushing a block up an incline

    Homework Statement "Consider a 250 gram block on a 10 degree frictionless incline and in contact with a spring of constant 1.2 N/cm. If the block is launched from rest by the spring with an initial compression of 6cm, how fast is the block moving at the point of release from the spring? How...
  6. F

    Acceleration of a block on a moving wedge

    Homework Statement A block of mass 0.5Kg rests on the inclined surface of a wedge of mass 2kg. The wedge is acted on by a horizontal force that slides on a frictionless surface. If the coefficient of static friction between the wedge and the block is 0.8 and the angle is 35 degrees, find the...
  7. M

    Percentage of Block Energy Dissipated

    Homework Statement During a vertical fall, a block's speed increases from 6 m/s to 8m/s over a 3 m distance. What percentage of the block's energy is dissipated due to air resistance over this distance? Homework Equations ##E_f = E_i## The Attempt at a Solution ##E_f = DE_i## ##KE_f + PE_f =...
  8. M

    Kinetic Friction Between Block and Surface (HW Check)

    Homework Statement A 10 g bullet is fired at 200 m/s into a 1 kg block after which they slide together 2 m on a horizontal surface. Determine the coefficient of kinetic friction between the block and surface. Homework Equations ##M_AV_{Ai} + M_BV_{Bi} = 0## ##WNC = ΔE## The Attempt at a...
  9. SciencyBoi

    A block placed in a horizontal hollow cylinder

    Homework Statement A block is placed inside a horizontal hollow cylinder. The cylinder is rotating with constant angular speed one revolution per second about its axis. The angular position of the block at which it begins to slide is 30° below the horizontal level passing through the center...
  10. T

    Block sliding down hill splits into two blocks

    I am currently working on this problem and I am stuck as to how to approach or solve it. The problem is that a block of mass 11000kg is sliding down a slope with a height of 1000m, angle of 40 degrees and the coefficient of friction between the block and the slope is 0.1. The block splits...
  11. C

    Mechanical energy of a block sliding on a circular path

    Homework Statement ( The following problem is taken from kleppner's " Introduction to mechanics" ) ( The question in the book talks about the velocity but my confusion is related to the Energy ) Homework Equations Conservation of Mechanical energy : Ef - Ei = 0 Consevation of Momentum : Pf -...
  12. S

    Simplifying transfer function block diagram

    Homework Statement Simplify the block diagram. I uploaded a single image as it's the easiest way to do this problem. Homework Equations None at this stage. The Attempt at a Solution Please see the image.
  13. C

    Forces on the slope of a triangular block

    Homework Statement I uploaded the question as an attached file. Homework Equations Fz = mg , F = ma , The Attempt at a Solution The slope : x Perpendicular to the slope: y I thought the Y forces can be neglected because the normal force counters the y component of the gravitational force...
  14. F

    Block on an inclined plane that is accelerating sideways

    Homework Statement [/B] A block of mass m rests on an inclined plane with angle o accelerating to the right with acceleration a. The coefficient of static friction is u.Homework Equations For what range of a does the block remain at rest on the plane. The Attempt at a Solution [/B] I started...
  15. A

    I Eigenvalues of block matrices

    If there is matrix that is formed by blocks of 2 x 2 matrices, what will be the relation between the eigen values and vectors of that matrix and the eigen values and vectors of the sub-matrices?
  16. T

    What do polarisation lens block?

    Electromagnetic waves are created by a accelerating charge that induces a changing electric field, that induces a changing magnetic field which propagates together through space. The electric and magnetic field are at right angles to each other. Polarisation blocks all but one plane of the...
  17. bdolle

    Understanding the Trigonometry of an Inclined Plane

    <Moderator's note: Moved from a technical forum and therefore no template.> I don't understand the math here which is troubling considering I got A's in calc 2 and 3... I tried to divide both sides by cos(theta) and solve for tantheta. but that gives something different. Also, what does...
  18. A

    Calculate speed of block at the end of the ramp

    Homework Statement A mass of m = 1.40 kg is placed on a 2.00 m ramp. The angle of the ramp can be adjusted by changing the height of the top of the ramp. In reality there is a small amount of friction between the block and the ramp: μs = 0.261, μk = 0.119. If the ramp (with friction acting)...
  19. K

    Block sliding up an inclined plane

    1. The problem statement, all variables, and given/known data A block with an initial speed of 20.0m/s slides up a ramp with an incline angle of 30º. (a) (2 points) Write the position as a function of time for motion up the surface of the ramp. (b) (2 points) Write the velocity as a function...
  20. J

    Calculating Torque for Tipping a Block: How Can I Determine the Required Force?

    1. The problem statement, all variables, and given/known data If I apply a force perpendicular to the side of a 2D block at 1/2 its height with a fixed bottom corner opposite the applied force how much force will be required to tip the block?: Block Mass = M Block Width = W Block Height = H...
  21. S

    Dropping a Block on a Spring with Completely Inelastic Collision

    Homework Statement [/B] A block of mass, m, is dropped from height, h (above the plate), onto a plate of mass, M, which is attached to a spring with spring constant, k. The block sticks to the plate and the system starts to oscillate. What is the amplitude of the oscillations. Homework...
  22. Abdul Wali

    MATLAB Matlab Derivative block analysis and filter design

    Hi, May someone helps me regarding this!? i have a controller which will control AC motor as attached. in this controller, a stage comes where I need to use a Derivative Block before point 'B' as shown in the attached picture " controller block diagram" [...
  23. Alexanddros81

    Pytels Dynamics 12.26: Block moves along the x-axis

    Homework Statement A 0.1-kg block moves along the x-axis. The resultant of all forces acting on the block is F = -1.2tiN, where t is in seconds. When t=0, x=0 and v=54i m/s. Determine the distance traveled by the particle during the time interval t=0 to t=4s. Homework EquationsThe Attempt at...
  24. L

    Finding Vmax of a Block in SHM: Mass, Spring Constant, and Distance

    Homework Statement A block with mass m=200g is attached to a spring with a elastic constant of k=5.0 N/m. The block is pushed at a distance x=5.00cm of its equilibrium position, in a surface with no friction. Then its dropped of that position. Assume for t=0s that the block is at rest. What is...
  25. T

    I Is Time an Illusion? Exploring the Block Universe Theory

    Einstein said, "The distinction between past, present and future is only an illusion, even if a stubborn one." That's my problem--that illusion is so vivid and stubborn. Paul Davies said in his book "About Time": There is only one rational conclusion to draw from the relative nature of...
  26. V

    Acceleration of a frictionless block on a frictionless wedge

    Homework Statement There is no friction between any surfaces mass is known. Find acceleration of the blocks. Homework Equations F=ma The Attempt at a Solution I'm almost certian Amx=g sin θ AMy=0
  27. CassieFordham

    B How high does a wall need to be to block smoke?

    A smoker just moved into the mobile home next to the one I live in, and insists on smoking in his yard. I want to build a wall between us to block the smoke. I don't know how to calculate how high the wall needs to be, to keep the smoke from blowing into my yard. Can anyone help me to figure...
  28. V

    Newton's laws of motion -- finding the velocity of a Block in a pulley system

    Homework Statement Determine the speed with which block B rises in figures if the end of cord at A is pulled down with a speed of 2ms^-1 Homework Equations Given Velocity downwards at A=2m/s The Attempt at a Solution Really stuck... Couldn't even start the question solving...I know all...
  29. S

    Statics: pushing a block up a wall w/ friction

    Homework Statement They ask for the smallest force P to apply if neither block is to slip. Coeff. of friction given as 0.25. The 20KG block is 196N; the 10KG block is 98.1N [/B]Homework EquationsThe Attempt at a Solution [/B] If we start at the 10KG block: Sum of forces x: N + cos26.6P –...
  30. N

    News London Tower Block Fire: Latest News Updates

    http://www.bbc.co.uk/news/uk-england-london-40272168
  31. NoahCygnus

    Motion analysis of an accelerating wedge and a block

    I don't understand the motion of an accelerating wedge and a block. I'd really appreciate if you make me understand the motion in both an inertial and a non inertial reference frame. Here's a figure I have made, a0 is the acceleration on the wedge with respect to an inertial frame, towards right.
  32. NoahCygnus

    Find the speed of the descending block

    Homework Statement So, we have a ring 'A' having mass 'm' that can slide on the horizontal rod. It is attached to a massless string, whose other end is attached to a block of mass 'M = 2m'. 'B' is a massless and frictionless pulley. The problem states that at an instant, the string between...
  33. B

    Pulley System on a Big Block: Solving for Acceleration with Zero Applied Force

    Homework Statement Find the accelaration of ##M_1## in the given system if ##F = 0##. Homework EquationsThe Attempt at a Solution [/B] ##x_3 -x_1 = k \iff \ddot x_3 = \ddot x_1## and ##h - y_3 + x_3 - x_2 = l \iff \ddot y_3 + \ddot x_2 = \ddot x_3 \qquad (*)## h is the height of block...
  34. F

    What Forces Act on a Block in a Rotating Cylinder?

    Homework Statement A cylinder with radius R spins around its axis with an angular speed ω. On its inner surface there lies a small block; the coefficient of friction between the block and the inner sur- face of the cylinder is μ. Find the values of ω for which the block does not slip (stays...
  35. B

    Spinning block with decreasing radius

    Homework Statement A mass ##m## whirls around on a string which passes through a ring. Given that gravity is not present and initially the mass is at a distance ##r_0## from the center and is revolving at angular velocity ##\omega_0##. The string is pulled with constant velocity ##V## starting...
  36. C

    Magnitude of Force Exerted on Middle Block in a Three-Block System

    Homework Statement Blocks of 1.0, 2.0, and 3.0 kg are lined up on a frictionless table with a 12-N force applied to the leftmost block. What's the magnitude of the force that the rightmost block exerts on the middle one? The blocks are lined up in such fashion: [1][2][3] and the 12 N force...
  37. R

    I Arithmetic Block in Shor Algorithm

    Hello everyone! So I was looking at Shor Algorithm for prime factorization and I have some doubts in the arithmetic part. Let's define a function f that : f(x) = ax mod N. The middle step in shor algorithm is to calculate, simultaneously, all values of f. In some papers and books, I saw some...
  38. H

    Energy and Friction in a block

    Homework Statement Homework Equations The block has potential energy U at the top of the ramp, and this is transferred to kinetic energy K at the bottom, which is then trasnfered to work done by friction, Wfr. U = K Conservation of energy K = Wfr Conservation of energy g = 10 m/s2The Attempt...
  39. T

    Net Force acting on block on incline

    Homework Statement A 6.50 kg block is placed on an inclined surface. The coefficients of static and kinetic friction between the block and the surface are 0.685 and 0.485, respectively. The incline makes an angle of 18.8° relative to horizontal. The block is at rest and remains at rest. What is...
  40. Dusty912

    Find the velocity of block a using vector method.

    Homework Statement (Picture attached) Question 1: The system starts at rest. Block a accelerates towards the bottom the the rod. Find the velocity of the block when it is at the bottom of the rod using the "vector method". So this was my midterm question today. I knew how to figure out how...
  41. S

    A block of mass m=0.2 kg, is pushed by a spring of stiffness k=300 N/m

    I am currently taking a physics class and I'm studying for the final and I've been stuck on this problem and haven't been able to find help from the book nor help from online. The professor said the answer was .56m, but I've been trying formulas for about an hour now and haven't been getting...
  42. M

    A block lies on an inclined plane with an angle of elevation

    Homework Statement A block lies on an inclined plane with an angle of elevation theta. The inclined plane is frictionless, and the plane is accelerated to the left such that the block's height remains constant. What is the net force on the block? I'm having trouble figuring out how to draw the...
  43. D

    Contact force of block on a wall

    Homework Statement In this sketch, the mass m = 1.6 kg is pushed against a wall by force F, as shown, in the horizontal direction. The values of the coefficients of kinetic and static friction for the contact between are 0.81 and 0.84 respectively. The magnitude of F is slowly and continuously...
  44. R

    Block hung from vertical spring

    Homework Statement A block is hung from a vertical spring. The spring stretches (h = .0650 m ) for a particular instant in time. Consider the earth, spring, and block to be in the system. If m = .865 kg and k = 125 N/m, find the change in the systems potential energy between the two times...
  45. R

    Time period of a block hanging from a pulley

    Homework Statement :[/B] The figure shows a pulley block system in equilibrium. If the block is displaced down slightly from its position and released, find the time period of the oscillation. Assume friction is sufficient. I: moment of inertia of pulley k: spring constant R: Radius of pulley...
  46. M

    Control systems: Simplifying block diagram

    Homework Statement How to show a block diagram can be simplified to a standard first order form for the diagram shown in the image attached and the question is shown in 1.a Homework Equations Standard first order form K/(1+tD) where K gain and t is time constant The Attempt at a Solution...
  47. EthanVandals

    How Does Spring Compression Affect Kinetic Energy and Velocity of a Block?

    Homework Statement A spring that has a spring constant of 2000 N/m is compressed 5 centimeters from its rest position. If a 2.5kg block is placed on the edge of the spring and then released, what will the block's kinetic energy be once it has completely left the spring? How fast will the block...
  48. C

    B What Forces are Missing in a Balanced Block on a Floor?

    I've drawn the diagram of the forces exerted on and by a block resting on a floor. For now, it seems that the forces exerted on the block are balanced - thus it doesn't accelerate. The forces exerted on the floor are, however, not balanced. The floor is not accelerating downwards, I must then...
  49. AilingLore21

    Negative Values of the Frictional Force?

    Homework Statement Ignore B & C for now The block in the figure reaches a velocity of 40 m/sec in 100 m, starting from rest. Compute the coefficient of kinetic friction between the block and the ground. W = 100N F = 40 N 2. Homework Equations ∑Fy = 0 so Normal Force = Weight ∑Fx =...
  50. R

    Spring block system on inclined plane

    1. Homework Statement : The block of mass m1 as shown in the figure (pic attached)is fastened to the spring and the block of mass m2 is placed against it. a)Find the compression of the spring in equilibrium position. b)The blocks are pushed a further distance (2/k)(m1 + m2)g sinθ against the...
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