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