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Flashcards in Kinematics & Energy Deck (35):
1

Power =

= work/time
= ΔKE/time
= forcecosθ*velocity

2

Work =

= ΔKE
= Fdcosθ
= power*time

3

ΔKE =

= ½ mv^2

4

Is momentum conserved if the object is acted on by external forces?

no

5

Gravitational force between 2 masses?

= GMm/r^2

6

circumference =

= πd

7

Distance and speed are both ______, meaning they represent _______ but not _______ and can never be _____.

Scalar
magnitude but not direction
can never be negative

8

Δx =
(projections)

Δx = v0t + ½at^2
Δx = ½v0t + ½vt

9

v^2 =
(projections)

v^2 = v0^2 + 2aΔx

10

v =
(projections)

v = v0 + at

11

At the apex of a projection, v= ? and a= ?

v = 0
a = g

12

Horizontal component of velocity =

v*cosθ

13

Vertical component of velocity =

v*sinθ

14

If initial and final elevations are the same, Δx =

Δx = (v0^2/g)* sin2θ

15

ΔPE =

mgh

16

total mechanical energy =

PE + KE

17

Other than in nuclear fusions, total energy is always _______

conserved

18

energy/work dissipated by friction

– µkmgL

19

Newton's 1st Law

constant velocity continues indefinitely if net force = 0

20

Newton's 2nd Law

f=ma

21

Newton's 3rd Law

equal & opposite force

22

Ff=

Ff = µ*Fnormal

23

How do scales measure weight?

by finding the normal force

24

If an object is suspended and not moving, what can you say about the forces?

Horizontal components must be equal & opposite

Vertical components must be equal & opposite

25

the work done by centripetal force on any object moving in a circle is _____

0

W=Fdcosθ, since F is towards center of circle and d is traveling tangential to circle, they are always perpendicular to each other, and cos90º=0

26

Torque =

= Frsinθ

(r = distance to fulcrum)

27

to calculate torque when mass is distributed uniformly, position torque at the ____________

center of mass

28

If an object is in rotational equilibrium, what can you say about the torque?

torque clockwise = torque counterclockwise

29

Angular momentum L = ?

L = mvR

30

what are 2 examples of non conservative forces?

air resistance
friction

31

Efficiency =

energy out / energy in

32

moment of inertia =

tendency to resist angular acceleration/torque needed to rotate

33

what does a higher moment of inertia mean?

high kinetic energy

34

density of a human is proportional to ______ (using weight in air and water)

Wair/(Wair-Ww)

35

average velocity =

Vavg = (v0 + v)/2