Blocks Definition and 767 Threads

  1. D

    Lagrangian moving blocks problem

    Homework Statement 1. Two identical blocks A and B with mass m are joined together by a taut string B of length `. Block A moves on a frictionless horizontal table and block B hangs from the string which passes through a small hole in the table as shown in the figure. (a) Using polar...
  2. gracy

    Why Is Static Friction Acting on Block B?

    Homework Statement ;Given in the figure are two blocks A and B of weight 20 N and 100 N, respectively. These are being pressed against a wall by a force F as shown. If the coefficient of friction between the blocks is 0.1 and between block B and the wall is 0.15, the frictional force applied by...
  3. gracy

    Force Applied -- General doubt about pushing 2 blocks on a floor with friction

    Force" F"is applied on M1 .Although force applied is not directly on M2,but it will also experience this force" F" via M1,right? But I don't think it is correct.Because it implies that no matter how big the force on M1,the net force on M1 will always remain zero.And there will be unbalanced...
  4. radiantvibe

    Two Blocks Inelastic Collision with Spring

    Homework Statement A solid block of mass m2 = 8.1 kg, at rest on a horizontal frictionless surface, is connected to a relaxed spring. The other end of the spring is fixed, and the spring constant is k = 230 N/m. Another solid block of mass m1 = 4.0 kg and speed v1 = 5.1 m/s collides with the...
  5. D

    Tension Rope and Blocks Problem

    Homework Statement Two blocks, each with weight w, are held in place on a frictionless incline as shown in Figure. In terms of w and the angle a of the incline, calculate the tension in the rope connecting the blocks Homework Equations T = mg The Attempt at a Solution I cannot for figure out...
  6. M

    Kinetics Problems -- Blocks on inclined plane

    Homework Statement Problem 1: A block of mass m = 15 kg from rest on an incline of 20 °. It is assumed that static and dynamic friction coefficients are respectively μs =0.4 and μk = 0.2. a force P is then applied (P = 30 N) on the block as shown in Figure 1 . a) Will the block slide? (...
  7. gracy

    Where Am I Going Wrong in Calculating Minimum Coefficient of Friction?

    Homework Statement :[/B] block M slides down on frictionless incline .Find the minimum co efficient of friction so that m does not slide with respect to M.Homework Equations :acceleration of the system=total driving force/total mass: [/B] The Attempt at a Solution m does not slide with...
  8. D

    Mechanical energy of frictionless pulley

    Homework Statement In the system shown, the block M (mass of 15.65 kg) is initially moving to the left with a speed of 3.4 m/s The mass of m is 8.26 kg and the coefficients of friction are μs=0.411 and μk=0.304. The string is massless and the pulley is massless and frictionless. How fast will M...
  9. H

    A spring and two blocks with kinetic energy

    1. I have two blocks, one that is 1.6 kg moving left at 3.00 m/s and the other is 2.1 kg moving right at -1.74 m/s, and they are compressing a block with a spring constant of k=600 N/m. I'm supposed to be finding the distance that the spring is compressed at that instant, and I know that...
  10. Q

    Problem of fluid -- Blocks, pulley, two fluids

    Homework Statement dynamic viscosity 1 = 1125 2 kgf-s / m2 , dynamic viscosity 2 = 62.5 2 kgf-s / m2 , Areas: A1 = 20 cm2 , A2 = 50 cm2 W1 = 15 Kgf, W2 = 40 Kgf. The block (2) is displaced downwards with a constant speed of 80 mm / sec, whereas linear velocity distribution determined: 1) The...
  11. T

    Forces; Two blocks connected by a pulley with friction

    Homework Statement A massless rope is attached to Block A, which as mass m_A and rests on a horizontal surface with coefficient of kinetic friction u_k. The rope passes over a frictionless, massless pulley and Block B is attached to the other end. When the blocks are released, Block A moves to...
  12. _N3WTON_

    Kinetics: Two Blocks and a Spring

    Homework Statement Suppose a block of Uranium and a block of Radium, both with edge length \lambda , are pushed to the head of an un-stretched spring (spring constant k , un-stretched length \delta _0 ). The combination, pushed \delta farther, compresses the spring. Upon release, the...
  13. S

    Would you -- drawing of wood blocks and a ruler to measure a lens

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown. Also, thread title edited to make it more descriptive. > The question is asking me to draw a diagram to show how, in the laboratory you would use two rectangular blocks of wood and a metre rule...
  14. L

    Blocks attached with spring is released from rest

    1. Consider the situation shown in figure. Initially the spring is unstretched when the system is released from rest. Assuming no friction in the pulley, find the maximum elongation of the spring. https://drive.google.com/file/d/0B3FvaDRwJ2neQWtBU3JrazVTeEU/view?usp=sharing Homework...
  15. L

    Tension in a string between two blocks

    Homework Statement Two masses M1 = 6.90 kg and M2 = 3.10 kg are on a frictionless surface, attached by a thin string. A force of 48.1 N pulls on M2 at an angle of 31.3° from the horizontal as shown in the figure. Calculate the tension T in the string. Homework Equations T=ma a=g(m2/(m1+m2))...
  16. H

    Maximum separation between blocks on spring

    Homework Statement Two blocks, each of mass m, are connected on a frictionless horizontal table by a spring of force constant k and equilibrium length L. Find the maximum and minimum separation between the two blocks in terms of their maximum speed, vmax, relative to the table. (The two blocks...
  17. K

    Two stacked blocks sliding down an inclined plane

    Homework Statement "You are lowing two boxes, one on top of the other, down a ramp. Both boxes move together at a constant speed. The coefficient of kinetic friction between the ramp and the lower box is 0.430, and the coefficient of static friction between the two boxes is 0.779. The lower box...
  18. B

    Acceleration of massless pulley and blocks

    Homework Statement Consider a situation I'm curious why is that the massless pulley's acceleration is just the avarage of acceleration of m1 and that of m2? ab=(a1+a2)/2 Homework Equations Forces acting on pulley are Tc-2Ta=0 (because pulley is massless, force can't give it acceleration)...
  19. H

    Solving 3 Block and Pulley Homework

    Homework Statement A block of mass m1 is on top of a block of mass m2. Block 2 is connected by an ideal rope passing through a pulley to a block of unknown mass m3 as shown. The pulley is massless and frictionless. There is friction between block 1 and 2 and between the horizontal surface and...
  20. P

    2 Cubic Blocks on a Right Triangle

    Homework Statement A right-triangular wooden block of mass M is at rest on a table, as shown in figure. Two smaller wooden cubes, both with mass m, initially rest on the two sides of the larger block. As all contact surfaces are frictionless, the smaller cubes start sliding down the larger...
  21. X

    Memorizing math and physics "building blocks?"

    I know a lot of courses like linear algebra have a ton of "building blocks" that one must memorize. Yes, you can derive these things yourself, but this often takes to long. Does anyone here use any tools like SuperMemo to memorize math theorems or physics laws/equations/etc? Also, I just...
  22. P

    Friction between 3 blocks conceptual problem

    Homework Statement Find the accelerations of each of the following three blocks: 2kg block, stacked on top of a 3kg block, stacked on top of a 7kg block When a force of 10N is applied on the 2kg block. Given: Coefficient of friction between 2kg and 3kg block is 0.2, coefficient of friction...
  23. S

    Weight of 2 Blocks on an Incline

    Homework Statement Block B rests on Block A. Block B is restrained with a string, while Block A slides down the incline. During the time Block A is between Block B and the inclined plane, Block A slides with constant velocity. If the weight of Blocks A and B are both w, and the coefficient of...
  24. C

    Stacked blocks on an accelerating elevator

    Homework Statement Four blocks of masses 20kg, 30kg, 40kg, and 50kg are stacked on top of one another in an elevator in order of decreasing mass with the lightest mass on the top of the stack. The elevator moves downward with an acceleration of ##3.2m/s^2## . Find the contact force between the...
  25. minimario

    Blocks, Collisions, and Friction

    Homework Statement A block of mass m lying on a rough horizontal surface is given an initial velocity of v_0. After traveling a distance d, it makes a head-on elastic collision with a block of mass 2m. How far does the second block move before coming to rest? (Assume that the coefficient of...
  26. D

    What Is the Minimum Hanging Mass Required to Keep a Block Stationary on a Wedge?

    1. A 1 kg wedge is pulled across a rough floor (uk=0.20) via contact with a 2 kg block as shown below. The shape of the wedge is that of an isosceles right triangle. a rope passes from the 2 kg block and over a mass-less and friction-less pulley and is attached to a hanging mass. Find the...
  27. R

    Friction problem -- 2 Blocks Sliding on a Surface

    Homework Statement A block of mass m=2kg and one of mass M=8kg have initial velocity zero. The friction coeffecient between m and M blocks is 0.3 Between block M and the surfasse there is no friction. L=3 metres F is a force constant and horizontal with magnitude 10 N, applied on block m and so...
  28. M

    Two Blocks connected by a rope

    Homework Statement The problem is from a worksheet and is a picture so I will try to describe the picture. A 3kg block and a 7kg block are connected by a rope and the 7kg block is falling from a table and the 3kg block is on the table. We are supposed to find the acceleration of the 3kg block...
  29. B

    Minimum Force of 86N to Move Two Blocks

    1. Homework Statement A 3.0-kg block sits on top of a 5.0-kg block which is on a horizontal surface. The 5.0-kg block is pulled to the right with a force ##\vec{F}##. The coefficient of static friction between all surfaces is 0.63 and the kinetic coefficient is 0.38. What is the minimum value...
  30. minimario

    Analyzing a Pulley System: Solving for Energy and Work

    Homework Statement Homework Equations ## W_{nc} = \Delta KE + \Delta PE ## ## PE = mgh ## ## KE = \frac{1}{2} mv^2 ## The Attempt at a Solution For Block B, ## \Delta KE + \Delta PE = \frac{1}{2} 100 v^2 + (-20)(g)(100) ## For Block A, ## \Delta KE + \Delta PE = \frac{1}{2} 50 v^2 + (20...
  31. F

    Tension in String between two blocks

    Homework Statement Block 1, of mass m_1 =2.6kg and block 2 of mass m_2=1.4kg are connected by a massless string. Block 2 then experiences a force F=18N acting in the postivive x direction and at an angle of \theta = 38° . The coefficiant of kinetic friction between the floor and both of the...
  32. A

    What is the Correct Concept for Solving the Stacked Blocks Problem?

    Homework Statement Homework Equations F= ma[/B]The Attempt at a Solution X does not slip. so friction exists. Friction should be equal to the force F applied so that according to Newton's 3rd law, the friction and F cancel out and X remains on Y. Is this the right concept?
  33. G

    Find force and coefficient of friction between 2 stacked blocks in motion

    Homework Statement The surfaces of two blocks are roughened so that they do not slide against each other when a force of 30N is applied to the bottom block. 1.Find the force of friction between the two blocks. 2. Find the minimum coefficient of friction needed between the two blocks so that...
  34. J

    Two Blocks and a pulley (Equation derivation)

    Homework Statement Look at the figure below. Derive the formula for the magnitude of the force F exerted on the large block (mC) in the figure such that the mass mA does not move relative to mC. Ignore all friction. Assume mB does not make contact with mC. Homework Equations F = ma...
  35. S

    Two Blocks attached by a string, on an incline

    Homework Statement In the diagram mA is equal to 3.00 kg and mB is equal to 1.07 kg. The angle of the inclined plane is 38.0° (a) Find Acceleration: 6.03 m/s^2 (got this part) (b) Find the tension Tb in the connecting string: Not sure Homework Equations (a) a = (F/mA + mB) (b) t =...
  36. B

    What Is the Maximum Force on the Upper Block to Prevent Slipping?

    Homework Statement Kleppner and Kolenkow "An Introduction to Mechanics (2nd ed.)" prob. 3.2: Mass MA = 4 kg rests on top of mass MB = 5 kg that rests on a frictionless table. The coefficient of friction between the two blocks is such that the blocks just start to slip when the horizontal...
  37. B

    What Is the Correct Mass of Block 2 in a Frictionless System?

    So I was sick last week for 3 classes and I really missed something and don't know what I am doing. Three blocks rest on a frictionless, horizontal table (see figure below), with m1 = 6 kg and m3 = 14 kg. A horizontal force F = 111 N is applied to block 1, and the acceleration of all three...
  38. END

    Tension between two sliding blocks

    Homework Statement The problem: Two blocks made of different materials connected together by a thin cord, slide down a plane ramp inclined at an angle θ to the horizontal as shown in the figure (block B is above block A). The masses of the blocks are mA and mB and the coefficients of...
  39. T

    Understanding the Ratio of Forces between Blocks in a Frictionless System

    Homework Statement Tom now pushes eight identical blocks on the horizontal and frictionless table (he’s compulsive). The force that block 1 exerts on block 2 is F12; the force that block 7 exerts on block 8 is F78. What is the ratio F12/ F78? Homework Equations F=ma Δp = FnetΔt The...
  40. C

    What is the tension in the rope used to pull two blocks with friction?

    Homework Statement Mass Ma lies on top of mass Mb, as shown. Assume Mb > Ma. The two blocks are pulled from rest by a massless rope passing over a pulley. The pulley is accelerated at rate A. Block Mb slides on the table without friction, but there is a constant friction force f between Ma and...
  41. E

    How Does Friction Affect the Reaction Force Between Two Blocks?

    Homework Statement There are two blocks against a wall on a frictionless table. I can't really manage a diagram, so please imagine this. There are two blocks, one of 5 kg and another of 10 kg, against each other. The 10 kg one is touching the wall. The frictional coefficient between the...
  42. I

    Solve Hanging Blocks Homework: Find Max Height

    Homework Statement How many blocks can you stack on top of each other before the tower falls? Each block has a mass m and a length l. The first block is on the table. The second block is stacked on top of the first but moved by 0.15L to the right. This pattern continues Homework...
  43. K

    Laws of Motion (Pulleys, blocks)

    Homework Statement A truck shown in the figure is driven with an acceleration a =3m/s2. Find the acceleration of the bodies A and B of masses 10 kg and 5 kg respectively, assuming pulleys are mass less and friction is absent everywhere. The Attempt at a Solution I have written three...
  44. J

    Blocks and pulley with mass - rotational dynamics

    Homework Statement Two blocks of masses m1 = 8.00 kg and m2 = 12.00 kg are connected by a string of insignificant mass. The string lies on a cylinder of mass 0.50 kg and a radius of 0.15 m. The coefficient of kinetic friction between m1 and the surface of an inclined plane is 0.10. The angle...
  45. V

    How Does the Period of Oscillation Change When a Block Detaches from the Wall?

    Homework Statement A system consists of two blocks, each of mass M, connected by a spring of force constant k. The system is initially shoved against a wall so that the spring is compressed a distance D from its original uncompressed length. The floor is frictionless. The system is now...
  46. C

    Insulation blocks mobile phone signals

    Modern foil covered foam insulation and coated window glass unfortunately blocks mobile phone signals rather well. I'm aware of solutions that use broadband and wifi to tunnel through it but this seems like a problem waiting for a better solution. Are there any good/cheap alternatives to...
  47. A

    Is This the Solution? A Review of Dynamics Pushing Blocks with Visuals

    Please look at pictures. Weirdly, my textbook does not give the answer to this question. Can you check my answer? Sorry for the really bad writing. If you ask, I can more clearly write it.
  48. T

    Solid Mechanics Stress Blocks- Principle blocks

    Hey guys, I would just like some confirmation that I got this question correct. Homework Statement For the stress block shown in Figure 3a, using the stress equations; a) Calculate the stresses sigmax' sigmay' and taux'y' on a stress block rotated 15° clockwise from the x-y axes...
  49. T

    Simply Supported Beam Stress Block Selection

    Homework Statement Hey guys, I have a test coming up soon, and our lecturer gave us a sample test. I am working through it, but we have not been given any answers to confirm if what we are doing is correct. The Question: "For the simply supported beam (with upstand) shown in...
  50. B

    How Much Friction Is Needed to Prevent Leakage in a Cubical Water Tank?

    Homework Statement A water tank is formed by sliding four identical cubical blocks together. All edges are watertight. Each block has mass M and is L meters on each side. You wish to fill the tank to its brim, i.e. to depth L. What is the minimum coefficient of static friction between the...
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