Chapter 7: Kinetic + Work (Exam 3)

Question 1

What is kinetic energy?

Answer 1

Energy in motion

Question 2

What is potential energy?

Answer 2

Energy at a position (rest)

Question 3

What is the variable for kinetic energy?

Answer 3

K

Question 4

K =

Answer 4

1/2mv^2

Question 5

What are the units for K?

Answer 5

1kg m^2/s^2 or joule (J)

Question 6

What is the definition of work?

Answer 6

transfer of energy through a force

Question 7

What sign (+/-) is work?

Answer 7

BOTH! either + or -

Question 8

What is the variable for work?

Answer 8

W

Question 9

W =

Answer 9

delta K = Kf-Ki

Question 10

What is the expanded delta K equation?

Answer 10

1/2mvf^2 - 1/2mvi^2

Question 11

If vf > vi and Kf > Ki, what is the sign of W?

Answer 11

+ (positive)

Question 12

In the ABcos(x) equation, what are the corresponding angles and signs of work?

Answer 12

theta > 90 degrees: w = negative (-)
theta < 90 degrees: w = positive (+)
theta = 90 degrees: w = 0

Question 13

What is the equation for multiple forces?

Answer 13

sigma F = F1 + F2 + … + Fn

Question 14

What is the equation for W using forces?

Answer 14

F1d + F2d + … + Fnd

Question 15

What is the equation for K using work?

Answer 15

delta K = W = W1 + W2 + … + Wn

Question 16

What is the equation for work done by weight?

Answer 16

Wg = mgdcos(x) = ± mgd

Question 17

What is the equation for work using integrals?

Answer 17

integral (xi to xf) F(x) dx

Question 18

What is Hooke’s Law?

Answer 18

Fs = -kx

Question 19

What is k?

Answer 19

spring constant

Question 20

What is the unit for k?

Answer 20

N/m

Question 21

What is the equation for Ws? (Hooke’s Law)

Answer 21

Ws = integral (xi to xf) [Fs dx] = -k integral (xi to xf) [x dx] = -1/2k(xf^2-xi^2)

Question 22

What is the variable for power?

Answer 22

P

Question 23

What is the equation for average power?

Answer 23

W/delta t

Question 24

What are the units for average power?

Answer 24

J/s or watt (w)

Question 25

What is the equation for power?

Answer 25

dW/dt

Question 26

Pv =

Answer 26

Fvcos(x)

Question 27

F(x) =

Answer 27

ma

Question 28

What is the equation for work using mass and acceleration?

Answer 28

w = integral (xi to xf) F(x) dx = integral (xi to xf) ma dx = integral (vi to vf) mv dv

Question 29

ma dx =

Answer 29

m(dv/dt) dx = m(dv/dx) dx = mv dv

Question 30

dv/dt =

Answer 30

dv/dx = dx/dt = dv/dx v

Question 31

overall, w =

Answer 31

delta K