KINETICS - linear impulse and momentum

Question 1

what type of quantity is impulse and momentum

Answer 1

vector

Question 2

what is impulse

Answer 2

a product of the force applied to an object or body, and the duration it is applied for

Question 3

what is the impulse momentum theorum

Answer 3

impulse of a force on an object is equal to its change in momentum of the object

Question 4

when a constant force is applied to an object for some time, what is affected

Answer 4

the objects velocity

Question 5

can calculate the impulse of a force by multiplying what and what is this

Answer 5

force magnitude x duration of force
-the area under the force time curve (or area of a square)

Question 6

what are 4 ways to increase impulse

Answer 6

-increase magnitude of force
-increase duration of the force application
-increase BOTH magnitude and duration
-increase the number of impulses

Question 7

describe the horizontal ground reaction force in running

Answer 7

when foot lands on ground this is known as the posterior-directed impulse
-negative phase
-frictional force that stops foot during landing
-the force reaction is in the negative direction whereas the f applied is in the positive direction
when foot is about to leave ground this is known as the anterior-directed impulse
-positive phase
-propulsive force used to propel the runner forward
-reaction force in the positive direction and applied force in the negative direction

Question 8

describe the net impulse of the horizontal ground reaction force in runnign

Answer 8

it is the sum of the positive and negative areas
-if equal, net impulse = 0 so no change in momentum or velocity
-if - > + then slowing down
-if - < + then speeding up

Question 9

in what 2 ways does forward velocity in a sprint start increase

Answer 9

• minimal negative impulse
• increase number of positive impulses
  -first few steps have a short swing phase allowing for a high step frequency (as many impulses as possible)

Question 10

what is momentum

Answer 10

the product of an objects mass and its linear velocity

Question 11

since the mass of a person does not change over a short period of time, we can use the impulse momentum theorem to compute what

Answer 11

final velocity of an individual after they experience an impulse

Question 12

we can use the impulse momentum theorem to compute the final velocity of an individual after they experience momentum if we can assume what 2 things

Answer 12

-initial velocity is 0
-mass is constant

Question 13

if you are given the impulse in the vertical direction, what must be done in the calculations that is not in the equation

Answer 13

the impulse of the body weight (N), must be subtracted from the gross impulse to obtain the net impulse

Question 14

does the impulse momentum relationship hold true in the angular sense

Answer 14

yes just diff. equation

Question 15

when calculating an impulse, what do you use if it is a non-constant force

Answer 15

the time integrel of the force
-or area under the force-time curve

Question 16

what is conservation

Answer 16

state in which a mechanical/physical property remains constant
-conservation of energy
-mass
-momentum

Question 17

what is the law of conservation of linear momentum

Answer 17

whenever the resultant froce acting on a body is equal to 0, the bodys linear momentum is conserved
-no unbalanced forces, no acceleration, no changes, constant

Question 17

when does conservation of angular momentum occur

Answer 17

whenever the resultant force acting on a body is a centric force (no external moments of force)

Question 18

how can we transfer or take up angular momentum

Answer 18

by rotating certain segments (to prevent rotation)