Mech Flashcards
1
Q
How to find centre of mass using integration? for (mean x)
A
π ∫ x y^2 dx /
π ∫ y^2 dx
2
Q
How to find centre of mass using integration? for (mean y)
A
π ∫ x^2 y dy /
π ∫ x^2 dy
3
Q
Limits for revolutions?
A
- where it crosses x axis (not 2π)
4
Q
Where is centre of mass for an isosceles triangle in the y axis?
A
-1/3 from base
5
Q
Find angle lamina makes with vertical?
A
- tan^-1 (x bar / y bar)
6
Q
SHM equations?
A
- v^2 = w^2(a^2 - x^2) (a is amplitude)
- acceleration = - w^2 x
7
Q
When to use x= a sin(wt)
A
- centre point where x=0
8
Q
How to calulcate SPEED in vectors?
A
- pythagoras
9
Q
When to use x= a cos(wt)
A
- at end point where x=a
10
Q
what does a equal to?
A
- dv/dt
- v dv/dx
11
Q
When 2 spheres hit what stays the same?
A
-wherever line of centres hit the opposite, if line of centres is on x plane then y stays the same
12
Q
How to calculate amplitude using time?
A
-when velocity is zero
13
Q
How to know what kind of damping from d^2x/dt^2 + 2k dx/dt + w^2 x ?
A
- overdamped k^2- w>0
- critically damped k^2 - w = 0
- underdamped k^2 - w < 0
14
Q
Impulse?
A
- change of momentum
