EXSC 550 Exam 3

what is the greek symbol used to denote angular velocity

"omega"

strain energy

(0.5) x kx^2

horizontal projectile component

(velocity)(cos*)

vertical projectile component

(velocity)(sin*)

Kinetic Energy (KE)

0.5 x mass x velocity^2 (Joules)

a 3 kg ball bounces at a speed of 2 m/s. What is it's KE?

0.5 x mass x velocity^2 (Joules)

projection angle

45* "optimal", not optimal for long jump because of the speed of approach

what is the acceleration of gravity?

9.81 m/s^2

kinetic friction

Friction between moving surfaces

when a body is moving around an axis of rotation, how can the acceleration of the body be resolved?

Into two perpendicular acceleration components (tangential & radial)

what is the equation to calculate power?

P = W/ delta t (Watts)

is it easier to push or pull an object?

PULL because it lowers NRF by not applying force downward into an object; however, we normally push because of a lack of handles or mechanisms with which to pull an object

the equation to convert angular velocity to linear velocity is:

V= radius of rotation x angular velocity

what is the equation to calculate work?

W= F x d (Joules)

a 59.1 kg person walks up 33, 22cm high stairs in 23 seconds. What is the work and power of this individual?

W= F x d (Joules) P = W/ delta t (Watts)

radial acceleration

component of acceleration of a body in angular motion directed toward the center of curvature; represents change in direction

what are the units for angular speed and velocity?

degrees/second

radius of rotation

distance from the axis of rotation to a point of interest on a rotating body

what is x^2 in the strain energy equation?

distance of deformation

instant center of rotation

exact center of rotation changes with angles because joints are asymmetrical resulting in linear displacement

Newton's law of reaction (3rd)

for every action, there is an equal and opposite reaction

friction

force action between two surfaces in the direction opposite motion or motion tendency

type of surface

impacts the amount of friction generated (ice v grass, using gloves in sports like golf, baseball, soccer, waxing a snowboard)

surface area

increased surface area= increased friction

what are the units for momentum?

kg m/s

what are the units for acceleration?

m/s^2

Potential Energy (PE)

mass x acceleration of gravity x height (Joules)

a 55 kg barbell moves 2 m. what is its PE?

mass x acceleration of gravity x height (Joules)

momentum

mass x velocity

maximum static friction

maximum amount of friction that can be generated between two stationary surfaces

factors affecting friction

normal reaction force, type of surface, surface area

what are the units for angular displacement?

normally degrees, radians will be used only if converting from angular to linear measurements

Between what two nature of impacts does a collision spectrum exist?

perfectly plastic and perfectly elastic impact

normal reaction force

perpendicular to two surfaces in contact increase in NRF = increase in friction *normally NRF= weight

factors affecting trajectory

projection angle, speed, and relative projection height

what is k in the strain energy equation?

spring constant based off the shape and material of an object

angular distance

sum of all angular changes, scalar

relative projection height

the difference between projection height and landing height

trajectory

the flight path of a projectile

perfectly plastic impact

total loss of system velocity

perfectly elastic impact

total system velocity is conserved

True/False: direct collisions occur in the direction of the greatest momentum

true

Acceleration

v2-v1/ delta t

why do we not use the RHR (right hand rule)?

we do not use the RHR to provide direction orientation for analysis because we have more precise, exact scientific language like flexion, abduction, internal rotation to provide direction

impact

collision with a large exchange of force over a small time period that is affect by momentum and the nature of impact

10(cos45) and 10(sin45) both equal 7.07 m/s. Why does this occur?

Because 45* is one half of 90*, so cosine and sine values are equal

Newton's law of inertia (1st)

a body maintains a constant state of velocity or rest unless acted upon by an external, net force (sufficient enough to cause motion)

Newton's law of acceleration (2nd)

a force applied to a body causes an acceleration of that body of a magnitude proportional to the force, in the direction of the force & inversely proportional to the body's mass

tangential acceleration

a straight line that touches but does not cross a curve

using the same softball pitcher, what is the total acceleration on the ball at the release point?

a= square root of (at^2 + ar^2)

what is strain energy based off of?

an deformed body's ability to return to normal shape

angular velocity

angular displacement/ delta t

angular speed

angular distance/ delta t

Kaitlin is swinging a softball bat to hit a homer in the 2019 Regionals. What is occurring to the angular and linear velocity of the bat?

angular velocity remains the same, linear velocity changes

what is the equation for radial acceleration?

ar= v^2/r

speed

as speed of an projectile increases, distance traveled at any given angle increases

what is the equation for tangential acceleration?

at= v2-v1/t

a windmill softball pitcher executes a pitch in 0.54 seconds. If her pitching arm is 0.65m long, what are the magnitudes of the tangential and radial accelerations on the ball just before release. Tangential ball speed is 20 m/s.

at= v2-v1/t ar= v^2/r

projectile

body in free-fall subject only to the forces of gravity and air resistance

energy

capacity to do work

angular displacement

change in angle from start to finish, vector