Term
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Definition
| effective forces of living organisms |
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| Why are biomechanics important? |
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Definition
| injury prevention, rehab, athletic performance, training improvement, and equipment improvement |
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| branch of knowledge that deals with living organisms |
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Definition
| study of forces and their effects on objects |
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| study of appearance or description of motion |
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| study of the actions of forces that causes the motion |
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| A base runner 15 m from the plate is heading home at 9 m/s. The catcher after chasing a wild pitch is 10 m from the plate and starts running at 5m/s. Who will reach home plate first? |
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Definition
Solution:
Catcher: time = 10m/(5m/s)
time = 2 s
Runner: time = 15/(9m/s)
time = 1.67 s
Runner by 0.33 s |
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| The hypotenuse of right triangle ABC is 6 cm long. What is the length of the other two sides. |
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Definition
Solution:
A = (6 cm) (sin 30°) = 3 cm
B = (6 cm) (cos 30°) = 5.2 cm |
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Term
| Describe a Rectilinear line |
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Definition
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| Describe a Curvilinear line |
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Definition
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Definition
| rotation around an axis[image] |
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Definition
| combo of linear and angular motion (includes most human motion) |
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Definition
Body or portion of a body that is deliberately chosen to be the focus of a particular biomechanical analysis
EX: throwing arm, kicking leg |
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| anatomical reference position |
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Definition
| erect standing position with all body parts facing forward |
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Definition
| forward and backward movements occur |
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Definition
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| rotational movements occur |
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Definition
| points of interest identified with respect to the origin in 3 dimensions |
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Term
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Definition
quantity of matter composing a body
represented by m
units: kg (lb/2.2) |
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Term
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Definition
tendency to resist change in motion
no units!
amount of inertia of an object is directly proportional to its MASS |
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Definition
push or pull- product of mass x acceleration.
Characterized by magnitude, direction, and pt of application
UNIT: Newtons N(1kg*1m/s^2) |
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Definition
| force=mass x acceleration |
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Definition
attractive force that the earth exerts on body
weight=m*a=-9.81m/s/s
units of wt are in units of force=Newtons |
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Term
| If I weigh 200lb what is my wt in Newtons? |
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Definition
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| A man on the moon has a mass of 100 kg. If the acceleration due to gravity on the moon is -1.62m/s2 is what is his mass on the Earth (g = -9.81m/s2)? |
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Definition
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| What is center of gravity? |
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Definition
point around which a bodies mass is equally balanced in all directions.
point at which weight vector acts |
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Definition
Rotational effect of force- torque and mom can be the same
TORQUE=FORCE X DISTANCE |
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Definition
product of force and time over which force acts
J=Ft UNITS: N
SMALL force acting for relatively LONG time
LARGE force acting for relatively SHORT time |
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Definition
force per unit of area which force acts: P=F/A
P=N/cm^2 |
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How much muscle force did the biceps brachii apply to the radius if the biceps produced 100 Nm of torque at a perpenHow much muscle force did the biceps brachii apply to the radius if the biceps produced 100 Nm of torque at a perpendicular distance of 3cm from the elbow joint?
dicular distance of 3cm from the elbow joint? |
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Definition
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Tennis shoe surface area=97 cm^2
Surface area of 12 Golf spike shoes= 0.36 cm^2
Tess weighs 223 N
What is the difference in pressure between the two shoe types? |
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Definition
Tennis shoe: 2.29 N/cm^2
Golf shoe: 619.44 N/cm^2
difference: 617.15
Rather have tennis shoe than golf spikes. |
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Term
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Definition
amount of space occupied by boy (width, ht, depth)
(cm^3, m^3, liters) 1liter=1000 cm^3
1qt= 57.75 in^3 |
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Definition
| mass per unit of volume- combine mass of body with body volume. Density (p)= mass/volume- kg/m^3 |
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Definition
| two forces forcing together EX: bones, placing flowers in a book |
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Definition
| pulling or stretching force directly axially EX: growing, ACL tear, achilles tendon during walking, stretchy bands |
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Definition
force directed parallel to surface; compressive and tensile forces act longitudinally.
EX: compound fractures ---> l
l <------- |
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Definition
| asymmetric loading produces tension on inside of longitudinal axis and compression-eccentric force applied to structure, structure bends, creating stress on ONE side and tensile stress on the other |
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Definition
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Definition
force unit of an area, which force acts- used to describe force distributed within a solid- UNITS: N/m^2
EX: spike |
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Term
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Definition
| effect of stress on material- changes shape |
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Term
| repetitive loading vs acute loading |
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Definition
repetitive loading- repeated application of subacute load that usually of relatively low magnitude
acute loading- application of a single force of sufficient magnitude to cause injury to a biological tissue
EX: repetitive stress fracture-- kevin ware compound fx |
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Definition
| forces are vectors, physical quantity posses both magnitude and direction |
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Definition
| result of vector addition of 2 or more forces |
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Definition
| result vector addition of ALL external forces |
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Definition
| forces that have the same line of action, NOT necessarily in the same direction |
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Definition
| time, distance, and mass speed ONLY about magnitude NOT direction |
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Definition
| process of determining a single vector from two or more vectors by vector addition. Composition of vector with the SAME direction requires adding their magnitudes. |
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| A weight lifter (mass = 100 kg) holds a barbell that weighs 50 lbs above his head. The vertical ground reaction force is 1000 N. What is the net force acting on the weight lifter? |
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Definition
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Definition
^
l
-----> + l TIP TO TALE METHOD
NON COLINEAR FORCES CANNOT BE ADDED THE SAME WAY AS COLLINEAR FORCES |
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| What is Vector resolution? |
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Definition
| replaces a single vector with 2 perpendicular vectors such that the vector composition of the two perpendicular vectors yields the original vector- vectors may be resolved into perpendicular components the vector composition of each pair of components yield the original vector |
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air resistance -15N, BW -700N, Friction 220N, Ground reaction force 820 N
What is the resultant force? What angle in which is he running? |
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Definition
resultant: 237.54
angle: 30.34 |
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| A shot leaves a throwers hand at 15 m/s and 42 degrees. How fast is the shot moving horizontally and vertically? |
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Definition
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| A baseball is thrown with a horizontal velocity of 18 m/s and a vertical velocity of 5 m/s. What is the resultant velocity (magnitude and direction)? |
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Definition
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an athlete applies 100N force 60 deg above the ground to a 40 N shot, calculate the magnitude and direction of the resultant force?
/l
/ l
/ |
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Definition
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Term
| What is position in regards to linear kinematics? |
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Definition
| location of object in space, uses a reference point, meters, vector quantity |
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Definition
length of path of motion, scalar quantity
EX: distance a skater travels may be measured from the track left on the ice |
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Definition
change in position; D= p2-p1
1 value for each dimension
EX: displacement of skater measured in a straight line from start to finish |
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| Speed and linear velocity |
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Definition
speed= (change) length/ (change) time or p2-p1/t2-t1
both measured in until of length divided by units of time |
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| velocity of swimmer in a river is the vector sum (resultant velocity) of the velocities of (swimmer) and current (velocity) |
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Definition
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| What is the average speed if you run a kilometer at 5 m/s and then walk a kilometer at 1 m/s? |
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Definition
| 1.67 m/s average total time |
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Term
| During gait, speed is the product of _____ _____ and ____ ____. |
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Definition
stride length, and stride frequency
m/stride x strides/sec=m/s |
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Term
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Definition
the rate of change in linear velocity; how velocity changes over time;means to speed up; directional terms are identified in terms of positive or negative;
a= (change) velocity/ (change)time or v2-v1/t2-t1 |
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| V1 = 0 m/s V2 = 10 m/s t = 3 s |
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Definition
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| V1= 7 m/s V2 = 0 m/s t = 0.7 s |
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Definition
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Term
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Definition
object in free fall: subject to gravity and air resistance;
projectile position, displacement, velocity, and acceleration can be clearly understood using equations of constant acceleration |
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| Rule 1: Projectile has both vertical and horizontal velocity will ALWAYS be a ________. |
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Definition
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| Rule 2: Horizontal and vertical components of projectile motions be treated ______. |
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Definition
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| Rule 3: gravity causes ________ ________ to decrease during the flight at a rate (acceleration) of -9.81m/s per second. |
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Definition
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| Rule 4: Vertical Apex = ? |
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Definition
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| Rule 5: Vertical initial (Vi) = |
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Definition
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Term
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Definition
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| Rule 7: horizontal velocity is constant throughout the flight. horizontal acceleration is? |
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Definition
| 0 because horizontal velocity doesn't change throughout entire flight this makes it 0 acceleration as the Hi is same as Hf.-HANG TIME |
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Term
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Definition
horizontal displacement or range of projectile is the main index of performance in many cases of projectile motion
dH= VHxt : indicates horizontal displacement depends on horizontal velocity and flight time. |
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Term
| What affects flight time? |
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Definition
Vertical speed at release, affected by angle of release
height of release |
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Term
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Definition
| magnitude of projection velocity |
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Term
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Definition
| difference between projection height and landing height |
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Term
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Definition
| direction of projection with respect to the horizontal |
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Term
| does increasing the height of release always lead to greater dH? How about increasing speed of release? increasing angle of release always lead to greater dH? |
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Definition
yes, increases time in air
yes, increases horizontal velocity and time
NO, height of release increases, optimal angle decreases |
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Term
How far will the shot travel?
Remember: dH = vH × t
Case I
speed of release = 12 m/s
height of release = 0 m
angle of release = 30 |
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Definition
Vvf= 6 m/s
Vvh=10.4 m/s
Tup= 0.6m/s
Tdown= 0.6 m/s
Ttotal=1.22 sec
Vh=1.83
H distance= 12.68 |
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Term
Case II
speed of release = 12 m/s
height of release = 2.1 m
angle of release = 30 |
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Definition
Vvf= 6m/s
Vvh=10.4 m/s
Tup= 0.61m/s
Ttotal=1.22 sec
Vh=3.93
T down= .90
T total= 15.7 sec
H distance= 15.7 m |
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Brian is attempting to high jump over a crossbar set at 2.13m. At the instant of takeoff, his vertical velocity is 4.0 m/s, and his center of gravity is 1.25 m high.
What is Brian’s vertical acceleration at the instant of takeoff?
How much time elapses from takeoff until Brain reaches his peak height?
Assuming that if Brian’s center of gravity is higher than the bar than he jumped over the bar, was Brian’s jump successful? |
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Definition
| Answers: a) -9.81m/s/s; b) 0.41 sec; c) 2.11 m |
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| If a soccer ball is kicked off of the ground, at 18 m/s, at angle of 15˚ above the ground, how long will that ball be in the air? Also, how far will the ball travel (horizontally) before landing? |
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Definition
| Answers: 0.95 s and 16.5 m |
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Term
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Definition
| Orientation of two lines, two planes, a line and a plane, two segments, etc. in relation to each other |
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Definition
| angular orientation of a segment relative to a fixed line or plane; usually vertical or horizontal |
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Definition
| angular orientation of a segment relative to a dynamic object; usually long axes of adjacent body segments |
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Term
Units of measurement:
degrees & radians
0=arc length/ r
ration of arc length divided by radius of circle
360 degrees:
180 degrees:
1 rad: |
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Definition
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Term
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Definition
rate of change of angular position or displacement
rad/s, deg/sec, rpm
average (ω) vs instantaneous (ω)
(ω)= change in arc length/ change in time |
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An athletic trainer examines an athlete’s knee. The athlete can flex her knee from anatomical position to 60 degrees, then return back to anatomical position. She performs this movement ten times. What is the corresponding angular displacement, in degrees and radians?
If the aforementioned range of motion can be performed in 11 seconds, what is the average angular velocity, in degrees/sec and rad/sec, during this time? |
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Definition
Angular displacement = 0 degrees and rad
Angular distance = 1200 degrees, 20.9 rad
Angular velocity = 0 degrees/sec and rad/sec
Angular speed = 109 degrees/sec, 1.9 rad/sec |
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Term
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Definition
rate of change in angular velocity
rad/s/s, deg/s/s
α=change in velocity/ change in time |
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| If a baseball pitcher can accelerate his humerus about the longitudinal axis, from 0 degrees/ sec to 7500 degrees/sec, in 300 milliseconds, what is the corresponding average angular acceleration? Report your answer in degrees/sec/sec and radians/sec/sec. |
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Definition
| Answer: 25,000 degrees/sec/sec and 436.3 radians/sec/sec |
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| A golf club is swung with an average angular acceleration of 2.5 rad/s2. What is the angular velocity of the club when it strikes the ball at the end of a 0.8 s swing? Report your answer in degrees/sec/sec and radians/sec/sec. |
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Definition
| Answer: 114.6 deg/sec and 2 rad/sec |
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Term
| Linear distance (arc length) ℓ |
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Definition
ℓ = Δθr
ℓ and r must be in the same units
θ must be in radians |
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Term
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Definition
v = ωr
Don’t forget the most important rule when using these equations: angles must be in radians!! |
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| If a baseball bat rotates 180 degrees about an axis of rotation, how far has the sweet spot traveled, if the distance between the sweet spot and axis of rotation is 50 inches? |
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Definition
180->rad 3.14->3.14*50 in=157.06 in
Answer: 157 inches
20.94 * 50=1046.67 in/sec |
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| What is the relationship between linear and angular acceleration? |
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Definition
| acceleration of a body in angular motion can be resolved into two perpendicular linear acceleration components |
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| What is tangential acceleration? |
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Definition
component of acceleration of angular motion direct along a tangent to the path of motion
at=v2-v1/t -- represents change in linear speed
at=rα -- relationship between at and α |
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| what is radial acceleration? |
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Definition
component of acceleration of angular motion toward the center of curvature
represent change in direction: ar=V2/r
ar=_ω_2_ |
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