Year 12s: what will be the first way you research your future options? >>

Edexcel AS/A2 Mathematics M1 - 8th June 2016 - Official Thread

Scroll to see replies

how are people getting 3Ns for impulse? i got 2.48 or something and it seems to work using kinematics,not sure how people are getting 3.5m/s for the velocity off the wall?

This is how I did it. A bit of resolving for the deceleration after the rebound, then using kinematics equations to find the speed immediately after the collision. Then shove into impulse equation.

R(->) F = 0.4a => R/8 = 0.4a, where R = 0.4g.

So, a = g/8 ms^-2

Then we must find the speed immediately after impact:
s=5 , u=?, v=0, a=-g/8 (<- +)
So you get: 0=u^2 - 12.25 => u=7/2 ms^-1

I = m(v-u) => I = 0.4(3.5-(-4) = 3 Ns.

Reply 1421

alardel

Does anyone have an official marking scheme?

Reply 1422

EpicTree

Original post by Darkseid1234

Is M exactly 42, I got 42,6?

same yeah I got .6 on the end too

Reply 1423

jtashcroft

Original post by ejk99

For the moments question I dot d = 1.6m and M = 66kg. Please could somone explain why this is incorrect?

I got the same thing!

Reply 1424

Jig1938

Original post by Shaunmcgown

What do people think that the raw marks needed to get 90 or 100 UMS??

I reckon 59 for an A

Reply 1425

BrainJuice

People who said impulse is 3kgms-1, I was wondering if it would actually be -3kgms-1 as the final velocity was negative (since the particle was moving in the other direction)?

Reply 1426

Hasib98

Original post by TSRPAV

how are people getting 3Ns for impulse? i got 2.48 or something and it seems to work using kinematics,not sure how people are getting 3.5m/s for the velocity off the wall?

Okay the ball hits the wall, as the question is asking for the impulse exerted on the ball by the wall; we need the velocity the ball HITS the wall with.

im order to do so we calculate the balls deceleration after hitting the wall which is done by resolving to the right.
Thereafter we use SUVAT to form an equation where V=0 as we are told it stops after 5m so S=5 and U=? and our A= -1.225
Then we use the appropriate equation and solve for U

then impulse :wink:

Reply 1427

greg2321

For the moments question which is out of 7 marks I got the incorrect answer of M = 105 and d = but as far as i can see I did the same method as everyone who got the write answer so I must have just made a numerical mistake so does anyone have any idea of how many marks I could possibly get out of 7?

Reply 1428

jtashcroft

Original post by BrainJuice

People who said impulse is 3kgms-1, I was wondering if it would actually be -3kgms-1 as the final velocity was negative (since the particle was moving in the other direction)?

It was the magnitude of the impulse so it doesn't matter if its positive or negative.

Reply 1429

Hasib98

Original post by BrainJuice

People who said impulse is 3kgms-1, I was wondering if it would actually be -3kgms-1 as the final velocity was negative (since the particle was moving in the other direction)?

asked for magnitude bro so signs are irrelevant, a positive value should have been stated

Reply 1430

angrybirdzzz

Original post by angrybirdzzz

For 8b, didn't the question ask for the force on the pulley due to the string? In which case the bearing is 225 degrees, as opposed to 45.

Anyone?

Reply 1431

txnilxnur

Original post by TSRPAV

how are people getting 3Ns for impulse? i got 2.48 or something and it seems to work using kinematics,not sure how people are getting 3.5m/s for the velocity off the wall?

By using f=ma in the direction away from the wall, you got an equation like -Friction = 0.4a (not sure what the mass was I forgot). Then work out friction as R = 0.4g and mu was given. So acceleration was like -1.225 something like that can't remember..
Then using suvat equations from the wall to when the ball came to rest:
u= ?
v=0
a=-1.225
s=5 (given)
then using v^2=u^2 = 2as to find u which was the speed which it came off the wall at... then using the equation for Impulse = mv-mu , as they were in opposite directions it worked out like
=0.4(3.5)+0.4(4)
=3
(where 3.5 is final speed after leaving the wall and 4 was speed before hitting the wall)

Reply 1432

E1Ephan7

I completely guessed 7a) F=2.5i and forgot to write j component. Showed no working. How many marks could i get? please someone?

Reply 1433

Tb3636

For the impulse queation I found the value of u using suvat. But didn't read the queation properly and didn't attempt the impulse. How many marks do you think I will lose? Guessing three. Cheers

Reply 1434

Questioner1234

Original post by angrybirdzzz

Anyone?

Yes it did ask for force on pulley due to string. I think what people mean is that the force is 45 to horizontal which is a bearing of 225.

Posted from TSR Mobile

Reply 1435

Hasib98

Original post by angrybirdzzz

Anyone?

that was the question yes but i dont think the answer is given in bearing form, just an angle respective of the direction

i just wrote diagonal cos i was confused LOOOL