My GMA Question Thread

[RKTR]

1)i think you meant value of P instead?

 4/8 =P/ 0.5
P=0.25 then round to one sig fig so P= 0.3

2)when something reaches maximum height, the velocity will be 0.
    v^2 = u^2 + 2ax
    0 =  9.8^2 + 2[-9.8](max height -150)
max height =154.9m

[alchemy]

1)i think you meant value of P instead?

 4/8 =P/ 0.5
P=0.25 then round to one sig fig so P= 0.3

Oh yes, I meant P. Sorry.
Can you justify your answer for this please?

[RKTR]

oops i did something wrong..

sin-1(4/8) =30

0.5 x tan(30) =0.288=0.3

[alchemy]

oops i did something wrong..

sin-1(4/8) =30

0.5 x tan(30) =0.288=0.3

Don't really understand what you did on the second line. 
Could you please explain?

[RKTR]

[alchemy]

1) A 20kg crate is pulled along a rough horizontal floor by a force, of magnitude 100N, applied upwards at an angle of 40 to the horizontal. The co-efficient of friction between the crate and the floor is 0.34. Find the acceleration of the crate.

2) Two blocks are connected by a light inextensible string. They are pulled across a surface, with a co-efficient of friction 0.12, by a constant force of 35N. Find the acceleration in the blocks and the tension in the string.

[b^3]

Resolve the forces in the vertical and horizontal directions, remembering that the sum of the forces in the vertical direction will be zero as the crate isn't moving up or down, and that the sum of the forces in the horizontal direction will give the net force (since the vertical forces cancel out), , and that the frictional force is given by .

Whatever that comes out to be.

See if you can have a shot at the second one, you'll need to form two equations, accounting for Tension in both and then solve the simultaneously.

[alchemy]

Thanks, but before I have a go at the second one, may I ask how you created that diagram (on what software)?

[Zealous]

Thanks, but before I have a go at the second one, may I ask how you created that diagram (on what software)?

That looks like Microsoft PowerPoint to me and with equations in textboxes (Insert -> Equation). Correct me if I'm wrong :p

[b^3]

That looks like Microsoft PowerPoint to me and with equations in textboxes (Insert -> Equation). Correct me if I'm wrong :p

(Sorry late reply, had myself banned so I could cram for uni exams).
It's powerpoint, but it's not all powertpoint. I can't stand the word equation editor, I cringe every time I see someone use it (it just looks... ugly, I really really hate it, it's not how you should be typing maths on a computer). So the labels are done in proper typeset, and well the the boxes and lines are powerpoint.

[M_BONG]

Can someone please explain what option "C" actually means, and why it is a true statement (in the attached photo). Thanks.

[TimmyC]

Can someone please explain what option "C" actually means, and why it is a true statement (in the attached photo). Thanks.

lmao.... disregarded wat u said because of the circled E LOL sorry

[RKTR]

Z^-1  means 1/z

[M_BONG]

Z^-1  means 1/z

That is what I did.

Let z= 3+2i

LHS= 1 / 3+2i

RHS = 3-2i / (3+2i)(3-2i)
        = 3-2i / 13

LHS does not equal RHS; false statement.

What is wrong with that?

[b^3]

That is what I did.

Let z= 3+2i

LHS= 1 / 3+2i

RHS = 3-2i / (3+2i)(3-2i)
        = 3-2i / 13

LHS does not equal RHS; false statement.

What is wrong with that?

It's a true statement, if you 'rationalise' the LHS and get the Im part in the numerator it comes out true.
e.g.