Work
What is Work?
The application of a force to move something over a distance
What is Energy?
The capacity to do work
What is Friction?
The force which opposes motion of one surface over another
Or
The resistance to motion created by contact of 2 surfaces
What is Angular Motion?
Angular motion takes place when a rigid segment or lever rotates around a fixed point or line in space.Path follows the Same angle ,Same direction ,Same time.
What is Angular Kinetics?
The study of forces which produce rotational movement or modify the factors
If F = 1430 N and D = 1.7 M. What is Work?
W = 1430 * 1.7 = 2431Nm
What is the other type of force work can be directly converted into
Kinetic Energy
What are the 2 factors that determine Kinetic energy
Mass and velocity of the body
What are the 2 cases where friction acts as a force
When Propulsive or braking forces is applied
or
As a response to an applied force
What are the 3 ways that describe angular motion
How far
How fast
How quickly
What are the 2 factors that determine The movement of force
Magnitude of the force
The force arm
If Wt = 800 N (Wt = m * g) and V = 4 m/s. What is Ke
KE = 1/2 * M * v ^2
Ke = 0.5(81.6)(4)^2
Ke = 652.8 Nm
What is the difference between Metabolic and Mechanical Work
Metabolic work is a muscle contraction resulting from biochemical energy whereas mechanical work is the effect of a mechanical force on a moving mass through a distance
What is the difference between Potential Energy and Kinetic Energy
Kinetic energy is the capacity of a body to do mechanical work because it is moving where as positional energy does mechanical work because of its position
What is the difference between static and kinetic friction?
Static friction occurs when there is no Motion
Kinetic friction occurs when one surface slides over another
Define Tangential velocity (Vt)
A linear velocity that occurs at some point along a segment
Vt = Wr/s * radius
What is the difference between a direct force and an eccentric forces
Eccentric force acts on a free floating body, products both translation and Rotation. Direct force acts through the center of gravity of a body
Given a football with a mass of 0.5 kg traveling at a velocity of 15.5 m/s is thrown. When the receiver catches the ball it will do work on the hand. What is the kinetic energy of the ball that is transferred into work? KE = Work
Ke = ½ (0.5kg)(15.5m/s)^2
Ke = 60 N*m = 60 J
The ball will do 60 N*m of work on the receivers hand(s)
Negative(muscle shortens in length): Concentric
Positive(muscle increase in length): Eccentric
Fill in the Blanks
While rising Potential energy ________ while Kinetic Energy _________. When falling vise versa is true
Increases, Decreases
What is the term used to describe the largest possible fictional force between two surfaces
Limiting Static Friction
For angular motion what directions denote positive and negative values
Positive is counterclockwise and negative is clockwise
How does eccentric forces result change if a fixed point is introduced
a result of translation and rotation to only rotation
Given Wt = 100N, sliding occurs at 63N, when is motion Impending (Fr is overcome by force)
Wt = Fn = 200N
Fr = Us * Fn = 0.2 *200 = 40N
At 39N there is no motion, at 40N there is impending motion
If f > 40 N then the object is sliding
W= F * D can be rearranged into F = W / D
Explain how force will be effected if work remains constant and distance is changed (increases or decreases)
If distance is increased the Force will decrease
if distance is decreased then Force is increased.
The energy of the object being caught is absorbed over a longer distance
Explained How Energy Is Transferred in Each Step in the following example. An archer with a bow draws the bow, releasing the arrow, the arrow flies and the arrow strikes a target.
Bow is Drawn
The archer provides metabolic energy to the bow
Energy is transferred from metabolic to strain energy
W = F * D
Arrow is released
Strain energy is converted to work on arrow
W → KE
The Arrow in Flight
The arrow has capacity to do work
KE = ½ * m * v^2
The Arrow Strikes the target
Arrow strikes target KE → Work
The arrow applies work (force over a distance) to the target
Explain each of the following Variables (Name and Meaning) Wt, F, Fr, Fn, Gnd
Wt is the Weight, is equal to Gravity * Mass
F is the force applied
Fr is the frictional force, is equal to F * Us (the coefficient of friction)
Fn is the force of normal
Gnd is the ground reaction force, It is another name for Fn
What is 1 Radian equal to in degrees
1 radian = 57.29 degrees
What are the alternate terms for the following
- Movement arm
- Movement Force
- Axis
- Movement arm = Force arm
- Movement Force = Torque
- Axis = Fulcrum
If R = 0.8m, t=1s. Find Vt after 1 rotation and a 2nd rotation (Theta = 1 and 2)
Wr/s = 1 R / 1 Sec = 1 Rad/s
Vt = Wr/s * r = 1rad/s*0.8m = 0.8 m/s
Wr/s = 2 R / 1 sec = 2Rad/s
Vt = 2 Rad/s * 0.8 m = 1.6 m/s