In lithic analysis, a subdivision of archaeology, a bulb of applied force (also known as a bulb of percussion or simply bulb of force) is a defining characteristic of a lithic flake. Bulb of applied force was first correctly described by Sir John Evans, the cofounder of prehistoric archeology. However, bulb of percussion was coined scientifically by W.J. Sollas. When a flake is detached from its parent core, a portion of the Hertzian cone of force caused by the detachment blow is detached with it, leaving a distinctive bulb on the flake and a corresponding flake scar on the core. In the case of a unidirectional core, the bulb of applied force is produced by an initiated crack formed at the point of contact, which begins producing the Hertzian cone. The outward pressure increases causing the crack to curve away from the core and the bulb formation. The bulb of applied force forms below the striking platform as a slight bulge. If the flake is completely crushed the bulb will not be visible. Bulbs of applied force may be distinctive, moderate, or diffuse, depending upon the force of the blow used to detach the flake, and upon the type of material used as a fabricator. The bulb of applied force can indicate the mass or density of the tool used in the application of the force. The bulb may also be an indication of the angle of the force. This information is helpful to archaeologists in understanding and recreating the process of flintknapping. Generally, the harder the material used as a fabricator, the more distinctive the bulb of applied force. Soft hammer percussion has a low diffuse bulb while hard hammer percussion usually leaves a more distinct and noticeable bulb of applied force. Pressure flake also allowed for diffuse bulbs. The bulb of percussion of a flake or blade is convex and the core has a corresponding concave bulb. The concave bulb on the core is known as the negative bulb of percussion. Bulbs of applied force are not usually present if the flake has been struck off naturally. This allows archaeologists to identify and distinguish natural breakage from human artistry. The three main bulb types are flat or nondescript, normal, and pronounced. A flat or nondescript bulb is poorly defined and does not rise up on the ventral surface. A normal bulb on the ventral side has average height and well-defined. A pronounced bulb rises up on ventral side and is very large.When explained visually, the bulb of percussion is visible on the ventral face as opposed to the dorsal face (where it is smoother) and considered to be on the "inside" of the parent core. The bulb of percussion is the primary feature that identifies the ventral surface of a flake or blade artifact. Locating its position reveals which is the proximal end of an artifact. Along the proximal end there may be the formation of ripple marks. These ripple marks allow for the direction traveled by the applied force through the lithic when it was detached. Typically, the striking of the flake is produced by knapping (or flintknapping), a process in which requires the user to chip away material from high-silica stones like "flint" in a carefully controlled manner with special tools to produce sharp projectile points or tools. A common characteristic that is associated with the bulb of applied force is a bulbar scar. This scar is from a small chip or flake on the bulb. This is known as an eraillure flake scar. It is produced during the initial impact of flake removal. Occasionally, there is more than one contact point on a striking platform which creates a series of superimposed waves. The eraillure flake is a chip removed through contact of a dominant force wave that creates the conchoidal flake and inferior waves. Bulb of applied force is not produced by bipolar technology or wedging initiation.
Homework Statement
A block of mass m1 = 2.0 kg is stacked on top of a block of mass m2 = 3.0 kg which is resting on top of a table
Both blocks and the table are made of the same material; so the coefficients of friction between all surfaces are the same
They are (attempt at a mew) ms = .60...
Homework Statement
What must be the applied force (25 degrees above the horizontal) in order to accelerate a block at 1.1 m/s^2, if the mass is 2kg and the coefficient of kinetic friction is .3?Homework Equations
F(net y)=Fn + Fav - W
Ff = μ x Fn
F(net x)=Fah-FfThe Attempt at a Solution
I've...
Homework Statement
Two blocks connected by a string are pulled
across a rough horizontal surface by a force
applied to one of the blocks.
The acceleration of gravity is 9.8 m/s2 .
1st block = 2 kg
2nd block = 8 kg
Force on second block at 52◦
μ = 0.29
[ 2kg ]-------[ 8kg ]/ 52 degrees
If each...
1. Hello. I am doing a practical assignment which involves a pully system with different masses on each side attached to a string. I have figured out acceleration via a = 2x/t^2 and then Force applied by F = (.42-.38)*0.286 which gives me 0.011N. However when I graph the final solution (I have...
Homework Statement
A worker drags a crate across a factoryt floor by pulling on a rope tied to the crate. The worker exerts a force of 450 N on the rope, which is inclined 38 degrees to the horizontal, and the floor exerts a horizontal frictional force on 125 N that opposes the motion. You...
When can you assume that gravity is the only "applied force" opposing friction?
Homework Statement
"Determine the stopping distance for a skier moving down a slope with friction with an initial speed of 24.7 m/s. The slope makes an angle of 5.02deg above the horizontal, and assume that...
I'm trying to work out a model for a spring mass system with a force acting at the centre of mass of the mass using Lagrangian mechanics. I can't work out the kinetic energy. I know the kinetic energy \text{KE}=\dfrac{1}{2}mv^2. I also have W=\int_a^b F \, dt.
Should I use \Delta \text{KE} +...
Homework Statement
What is the value of the force of friction?
Acceleration = 1m/s^2
Applied force = 5.5N
Homework Equations
:confused:
The Attempt at a Solution
:confused:
I know what to do if mass or a coefficient of friction were given, but unfortunately they're not...
Homework Statement
hey just having a hard time figuring out a question about tension and applied force:
A dock worker pulls two boxes connected by a rope on a horizontal floor, as shown in the figure (Intro 1 figure) . All the ropes are horizontal, and there is some friction with the floor...
Homework Statement
If a force of 45 Newtons is needed to overcome friction and the coefficient of friction=0.26, what is the mass of the object?
The Attempt at a Solution
So would I need to find the frictional force first? But then I can't use the equation: (frictional...
Hi
A block ( 0.5 kg ) is attached to a spring ( k = 40N/m ) on a frictionless table..
The spring is 0.6 meter long unstretched ..
A constant force (20 N ) is applied horisontaly causing the spring to stretch
1) question : what is the speed/velocity of the box after 0.25 meter ...
Homework Statement
A force of 10.0 N is applied at an angle of 30° to the horizontal on a 1.25-kg block initially at rest on a frictionless surface. a) What is the magnitude of the block’s acceleration? b) What is the magnitude of the normal force?
This was en example in my book. I...
Homework Statement
Box A
Mass=3.2kg
Force of Friction=2 Newtons
Box B
Mass=2.1kg
Force of Friction=1 Newton
Force applied 10.5 Newtons [horizontally].
http://img162.imageshack.us/img162/7697/f1qd1.png
Q. Find the magnitude of the force of contact between the two boxes...
Homework Statement
Assuming I have a simple body, like a box, with known center of mass, how do I find the applied force, through its center of mass that will cause the object to tip over? The object is at rest on a flat surface.
Known elements:
weight of object, static friction between...
a curler exerts a force forward on a 19kg curling stone and gives it an acceleration of 1.8m/s(squared) [forward]. the coefficient of kinetic friction of the ice on the curling stone is 0.080 [back]. calculate the value of the applied force. thank you in advanced
Homework Statement
What would happen to the coefficient of friction if the applied force was not horizontal to the surface?
Homework Equations
Ff=_{\mu}FnThe Attempt at a Solution
I am unsure of how to proceed with this question, but I am thinking that you can't have friction against a...
Homework Statement
A horizontal force of 50 N is required to pull and 8.0 kg block at a unifrom velocity across a horizontal wooden desk. Determine the coefficient of kinetic friction.
Homework Equations
F_{Net}=ma
The Attempt at a Solution
I put F_{Net} as 0, because accleration...
how do i find applied force if it not given?
how do i find force of friction if coefficient of friction is also not given?
how do i find coefficient of friction of objects on 3 different surfaces?
(what should be the variable?)
thanks so much
Homework Statement
Explain why applied force is plotted on the vertical axis of the graph even though it is the independent variable in a Hooke's Law experiment (involving a mass being attached to the spring)
Homework Equations
Fx = kx
The Attempt at a Solution
Maybe it's because...
Okay I am confuse on how i came to this conclusion and how i came to that answer.
A block of mass 2.50 kg is pushed 2.80 m along a frictionless horizontal table by a constant 12.0 N force directed 25.0° below the horizontal.
(a) Determine the work done by the applied force.
30.45J
(b)...
Does anyone know how to answer this question?
Question: How do i determine power generated by an applied force if it takes 9.0 s to push the box up the ramp.
I am given
mass=2.0kg
height of ramp= 2.7m
length of ramp= 5.3m
angle= 30*
constant force= 12N
What should i do I am stuck ! tell...
Wondering if someone could help me with my last set problem? I've been looking at it for quite some time now. The incoming force on the block is confusing me...as a result, I'm not sure how to set it up. I've worked it with the force parallel to the incline as well as perpendicular - but not as...
Hi, I need advice as to whether or not I solved this question correctly. I would really appreciate the feedback, etc... I really need to know if I did this right
QA: A 2kg object is attached to a spring and placed on a horizontal smooth surface. A horizontal force of 20N is required to hold...
hey everybody, i have an easy problem in friction, i just want to make sure if what i did is right; here is the problem:
A 22kg mass is slid up an incline of 71degree to the horizontal at constant velocity. If mu=.29, what is the applied force?
here is what i did:
Fgravity =...
A 115.0 kg box is pushed by a horizontal force F at constant speed up a frictionless ramp which makes an angle of 49.0 deg with the horizontal. Find the magnitude of the applied force F.
I can't seem to get this problem right. In the x-direction there is a push. Which I got mgsin(49).
In...