Kinematics & Energy

Question 1

Power =

Answer 1

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

Question 2

Work =

Answer 2

= ΔKE
= Fdcosθ
= power*time

Question 3

ΔKE =

Answer 3

= ½ mv^2

Question 4

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

Answer 4

no

Question 5

Gravitational force between 2 masses?

Answer 5

= GMm/r^2

Question 6

circumference =

Answer 6

= πd

Question 7

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

Answer 7

Scalar
magnitude but not direction
can never be negative

Question 8

Δx =

projections

Answer 8

Δx = v0t + ½at^2
Δx = ½v0t + ½vt

Question 9

v^2 =

projections

Answer 9

v^2 = v0^2 + 2aΔx

Question 10

v =

projections

Answer 10

v = v0 + at

Question 11

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

Answer 11

v = 0
a = g

Question 12

Horizontal component of velocity =

Answer 12

v*cosθ

Question 13

Vertical component of velocity =

Answer 13

v*sinθ

Question 14

If initial and final elevations are the same, Δx =

Answer 14

Δx = (v0^2/g)* sin2θ

Question 15

ΔPE =

Answer 15

mgh

Question 16

total mechanical energy =

Answer 16

PE + KE

Question 17

Other than in nuclear fusions, total energy is always _______

Answer 17

conserved

Question 18

energy/work dissipated by friction

Answer 18

– µkmgL

Question 19

Newton’s 1st Law

Answer 19

constant velocity continues indefinitely if net force = 0

Question 20

Newton’s 2nd Law

Answer 20

f=ma

Question 21

Newton’s 3rd Law

Answer 21

equal & opposite force

Question 22

Ff=

Answer 22

Ff = µ*Fnormal

Question 23

How do scales measure weight?

Answer 23

by finding the normal force

Question 24

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

Answer 24

Horizontal components must be equal & opposite

Vertical components must be equal & opposite

Question 25

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

Answer 25

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

Question 26

Torque =

Answer 26

= Frsinθ

r = distance to fulcrum

Question 27

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

Answer 27

center of mass

Question 28

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

Answer 28

torque clockwise = torque counterclockwise

Question 29

Angular momentum L = ?

Answer 29

L = mvR

Question 30

what are 2 examples of non conservative forces?

Answer 30

air resistance

friction

Question 31

Efficiency =

Answer 31

energy out / energy in

Question 32

moment of inertia =

Answer 32

tendency to resist angular acceleration/torque needed to rotate

Question 33

what does a higher moment of inertia mean?

Answer 33

high kinetic energy

Question 34

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

Answer 34

Wair/(Wair-Ww)

Question 35

average velocity =

Answer 35

Vavg = (v0 + v)/2