physics problems

Question 1

inclined plane formulas

Answer 1

Fg-parallel = mg sin theta 
Fg-perpend= mg cos theta

Question 2

center of mass

Answer 2

for x, y and z:

x = (x1m1) + (x2m2)…./ m1 + m2…..

Question 3

dot product

Answer 3

only magnitude
A x B = |A| x |B| x cos theta

theta=

Question 4

cross product

Answer 4

magnitude AND direction

A x B= |A| x |B| x sin theta

theta =

Question 5

Gravitational force

Answer 5

F = (Gm1m2)/ r^2
G=
r= radius

Question 6

torque

Answer 6

Tau = rF sin theta
r =
theta =

Question 7

Kinematics chart linear motion

Answer 7

v = (v0) +at 
x = (v0)t + (1/2)at^2 
v^2 = (v0)^2 = 2ax
x = vt

Question 8

vector components

Answer 8

x = v cos theta 
y = v sin theta 

for a right triangle w/ right angle at lower right

Question 9

how much heat required to completely melt object x

Answer 9

1. use q=mcat to raise the heat to melting point
2. use q=mL
3. add values

Question 10

the entropy of a system can

Answer 10

decrease when the entropy of surroundings decreases by just as much

Question 11

coffee cup calorimeter

Answer 11

usually isolated system

Question 12

heat of fusion vs internal energy

Answer 12

heat of fusion = heat req to melt solid

internal energy = irrelevant to heat transfer

Question 13

entropy is 0 when

Answer 13

in a reversible process

Question 14

work and pascals principle

Answer 14

W = F1D1

for double the work, the cross sectional area must be doubled

Question 15

Bernoilli’s airplane lift

Answer 15

speed of airflow is greater on top so less pressure on the top (less pushing down)
production of net upward force