M2 Centre of Mass

I am stuck on exercise 2B question 2e. Any help please.

geoffhig

I am stuck on exercise 2B question 2e. Any help please.

Usual method with

---Separate Masses------------------Total Mass
15------------------1------------------16
xbar----------------2.5-----------------2
ybar----------------1.5-----------------2

15xbar+ 2.5 =32
15ybar + 1.5 = 32

solve to get answer given (we hope)

Aitch

Edit:
[The "we hope" is not needed - I've checked the answer!]

Reply 2

geoffhig

how do you do questions 3,4,5 lol

Reply 3

Aitch

geoffhig

how do you do questions 3,4,5 lol

Not too much time right now. I might come back tomorrow unless some rising stars might like to chip in ??

Come on guys!

Aitch

[Edexcel text M2]

Reply 4

Aitch

Not too much time right now. I might come back tomorrow unless some rising stars might like to chip in ??

Come on guys!

Aitch

[Edexcel text M2]

q3a let a = θ/2

r=4, a = π/4

COM is (r.sina)/a from centre = 4.(1/√2)/(π/4)=3.60

other parts are similar. Just remember to get θ in radians and a is half of θ.
Then COM is (r.sina)/a from centre.

Aitch

Reply 5

Aitch

Not too much time right now. I might come back tomorrow unless some rising stars might like to chip in ??

Come on guys!

Aitch

[Edexcel text M2]

Q4e Sectors now.

θ = 45° = π/4 c.
a= θ/2 = π/8c

COM is (2r.sina)/3a from centre
=(20.sin(π/8))/(3π/8)
=6.50

other parts are similar.

Aitch

Reply 6

Aitch

Not too much time right now. I might come back tomorrow unless some rising stars might like to chip in ??

Come on guys!

Aitch

[Edexcel text M2]

Q5.

AB=1.5
BC=2.5
so AC=2

So you have a right-angled triangle

let A be (0,0), B be (1.5,0) and C be (0,2) Draw the triangle.

----separate masses-----------------total mass
----1.5-------2-------2.5-----------------6
x---.75-------0--------.75----------------xbar
y----0--------1--------1------------------ybar

so
(a)
2x1 + 2.5x1 = 6 ybar
ybar = 0.75

(b)
1.5x0.75 + 2.5x0.75 = 6xbar
xbar = 0.5

Aitch