LECTURE #10 - linear kinetics

Question 1

what are the three laws of motion ?

Answer 1

LAW #1 - law of inertia
LAW #2 - law of acceleration
LAW #3 - law of reaction

Question 2

what is the first law of motion ?

Answer 2

law of inertia

Question 3

what is the second law of motion ?

Answer 3

law of acceleration

Question 4

what is the third law of motion ?

Answer 4

law of reaction

Question 5

what is law of inertia

Answer 5

objects @ rest stay at rest and objects moving stay moving (momentum)

Question 6

what is the law of acceleration ?

Answer 6

the change of motion is proportional to the force impressed and is made in the direction of the straight line in which that force is impressed

Question 7

“change of motion” is used to define what term ?

Answer 7

acceleration

Question 8

if a net force is applied to an object then :

Answer 8

• object will accelerate in direction of net external force
• acceleration will be proportional to net external force & inversely proportional to its mass

Question 9

what does proportional mean ?

Answer 9

one goes up and one goes down

Question 10

when mass goes up what does it mean for acceleration ?

Answer 10

acceleration goes down (harder to move)

Question 11

FILL IN THE BLANK

measure of force is the ________

Answer 11

newton

Question 12

FILL IN THE BLANK using ↑ and ↓

__ motion : __ magnitude or __ duration

Answer 12

↑motion : ↑magnitude or ↑duration

Question 13

FILL IN THE BLANK
_________ is the amount of force it takes to accelerate a 1-kg object 1 m/s^2

Answer 13

1 newton

Question 14

N = what unit ?

Answer 14

1 kg * 1 m/s^2

Question 15

TRUE OR FALSE

N = kgm/s^2

Answer 15

TRUE

Question 16

what is the formula for law of acceleration ?

Answer 16

ΣF = ma

Question 17

what does “ΣF” stand for ?

Answer 17

net external forces

Question 18

what does “m” stand for ?

Answer 18

mass of object

Question 19

what does “a” stand for ?

Answer 19

acceleration of object

Question 20

define cause and effect relationships of law 2 :

Answer 20

• forces causes acceleration
• acceleration is the effect of forces

Question 21

what is impulse ?

Answer 21

product of force and time over which force acts

Question 22

FILL IN THE BLANK regarding impulse :

“when force is applied to a body, the resulting motion is dependent upon both the ___________ and _________ of force”

Answer 22

magnitude and duration

Question 24

what is the formula for impulse :

impulse = __ x ___

Answer 24

impulse = (F) (t)

Question 25

what are the units for impulse ?

Answer 25

(N)(s)

Question 26

define impulse :

Answer 26

product of a force and the time interval over which the force acts

Question 27

what two things do momentum changes rely on impulse ?

Answer 27

- magnitude of external force - length of time over which external force acts

Question 28

TRUE OR FALSE for momentum, change will be directly placated on momentum ?

Answer 28

TRUE

Question 29

the following is the formula for what ? m(v(f) - v(i))

Answer 29

momentum (newtons second law restated)

Question 30

TRUE OR FALSE during impact situations, we often control impulse to produce the desired outcome ?

Answer 30

TRUE

Question 31

FILL IN THE BLANK using ↑ and ↓ __ impulse = __ momentum = ___ jump hight

Answer 31

↑ impulse = ↑ momentum = ↑ jump high

Question 32

to have a change in momentum what must we see ?

Answer 32

- change of state of motion - increase time and abruptly stop (deceleration) - force incorporated for how long its being applied for

Question 33

define hard landing :

Answer 33

dissipating a large force over short time

Question 34

define soft landing :

Answer 34

dissipating a large force over long time

Question 35

what does GRF stand for ?

Answer 35

ground reaction force

Question 36

"change in momentum" is defined by what term ?

Answer 36

impulse

Question 37

what do we do to length to the amount of time to reduce force ?

Answer 37

lengthening the amount of time

Question 38

______ & ______ = force

Answer 38

action & reaction

Question 39

define the law of reaction

Answer 39

to every action theres always opposed an equal reaction: or, the mutual action of two bodies upon each other are always equal and directed to contrary parts

Question 40

what are the 4 interpretations of law of reaction :

Answer 40

- forces never act in isolation, always in pairs - forces are equal in magnitude - forces are in opposite direction - action (force) & reaction (counterforce) act on different objects

Question 41

what is the first interpretation of the law of reaction ?

Answer 41

forces never act in isolation, always in pairs

Question 42

what is the second interpretation of the law of reaction ?

Answer 42

forces are equal in magnitude

Question 43

what is the third interpretation of the law of reaction ?

Answer 43

forces are in opposite direction

Question 44

what is the fourth interpretation of the law of reaction ?

Answer 44

action (force) & reaction (counterforce) act on different objects - don't cancel each other out - may have different effect on the object

Question 45

what do GRF's contribute to ?

Answer 45

contribute to overuse injuries such as stress fracture and to diseases such as osteoarthritis