# Edexcel M4 Exam Discussion Thread [June 5th]Watch

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4 years ago
#141
(Original post by TeeEm)
....
Just quoting you in here as I noticed you're online, and the exam's tomorrow so this question is fairly urgent.

When doing problems of oblique collisions of two smooth spheres (of equal radii) how do you intuitively know the direction they move in after the collision?

Wouldn't this affect the equations you form (due to differing signs)?
0
4 years ago
#142
(Original post by ThatPerson)
Just quoting you in here as I noticed you're online, and the exam's tomorrow so this question is fairly urgent.

When doing problems of oblique collisions of two smooth spheres (of equal radii) how do you intuitively know the direction they move in after the collision?

Wouldn't this affect the equations you form (due to differing signs)?
A bit late to explain this but I always mark the "after velocities" to the "right" unless I have been told or it is implied that one rebounds.
Their true direction will come out in the "wash"
Look at some solved problems in my booklets
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4 years ago
#143
0
#144
****ing hell, I almost couldn't do question 6 because I didn't do enough past papers.

I wasted so much time on it, but at least I managed to do it.

Spoiler:
Show
1.
t = 37/2, d = sqrt(12.5)

2.
speed = sqrt(272) (16i+4j)
direction [from] = 104 degrees

3.
24.1 degrees

4.
540ln(5/2)-360

pi/3

6.
0, +- pi/6
stable (Actually unstable )

7.
w= sqrt(103)/16*u
1
4 years ago
#145
How was todays exam. can anyone post the answers ?
0
4 years ago
#146
It was unstable.

(Original post by simonli2575)
****ing hell, I almost couldn't do question 6 because I didn't do enough past papers.

I wasted so much time on it, but at least I managed to do it.

Spoiler:
Show
1.
t = 37/2, d = sqrt(12.5)

2.
speed = (272) (16i+4j)
direction [from] = 104 degrees

3.
24.1 degrees

4.
540ln(5/2)-360

pi/3

6.
0, +- pi/6
stable

7.
w= sqrt(103)/16*u
0
4 years ago
#147
I got the same answers (except unstable) I think! How did everyone find it?
0
4 years ago
#148
I got unstable, messed up question two tho.......
0
#149
(Original post by Gallax)
It was unstable.
(Original post by Human156)
I got the same answers (except unstable) I think! How did everyone find it?
(Original post by burianl)
I got unstable, messed up question two tho.......
****.
0
4 years ago
#150
Oh no i didnt, i just said that the wind blows on a bearing of 284 degrees
0
4 years ago
#151
I too messed up the second question.(it was really stupid mistake). I got unstable. And expected grade boundries ?
0
4 years ago
#152
i got stable with d2v coming out as -1/2 but im likely to be wrong. I got the speed w correct sqrt(106)U/16 but i didnt find it in surd form, i.e 0.63 U do you guys think ill get the marks?
0
4 years ago
#153
(Original post by NathanSE)
i got stable with d2v coming out as -1/2 but im likely to be wrong. I got the speed w correct sqrt(106)U/16 but i didnt find it in surd form, i.e 0.63 U do you guys think ill get the marks?
Yup that should be ok. What are you expecting the grade boundries to be ?
0
4 years ago
#154
(Original post by simonli2575)
****ing hell, I almost couldn't do question 6 because I didn't do enough past papers.

I wasted so much time on it, but at least I managed to do it.

Spoiler:
Show
1.
t = 37/2, d = sqrt(12.5)

2.
speed = (272) (16i+4j)
direction [from] = 104 degrees

3.
24.1 degrees

4.
540ln(5/2)-360

pi/3

6.
0, +- pi/6
stable

7.
w= sqrt(103)/16*u
Got the same, apart from. 2, shouldn't speed be the square root of(272
0
#155
(Original post by Gome44)
Got the same, apart from. 2, shouldn't speed be the square root of(272
Oh I just forgot.
0
4 years ago
#156
Anyone else get 15 degrees for question 3?
0
4 years ago
#157
I got destroyed, now I need to do well in M5 :'(
0
4 years ago
#158
Pretty easy paper I thought, 2 of the simplest relative motion questions they could of asked
0
4 years ago
#159
(Original post by Gome44)
Got the same, apart from. 2, shouldn't speed be the square root of(272
agreed
0
4 years ago
#160
0
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