M1 OCR (Not MEI) Exam - 9/06/2015

OP

Original post by buckeybarnes

ya i did the initial momentum and final momentum and got an answer to the velocity of Q, the did s=vt and added them together, that was the right method apparently but it says i worked out the velocity of Q incorrectly :/

What did you get for q?

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Reply 162

Original post by MsFahima

What did you get for q?

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1.59m

Reply 163

alexann95

2

Original post by buckeybarnes

do you know how to do 2ii? http://www.ocr.org.uk/Images/63190-question-paper-unit-4728-01-mechanics-1.pdf
i've almost got the method but i cant seem to get an appropriate answer

Ill post a picture of my answer soon, I'm just revising for my exam tomorrow so sorry for the slow replies.

Reply 164

rich1334

11

I feel too relaxed for this exam :tongue:

but after how FP1 and S2 went I think I only need 45-50 UMS to get an A overall 😄

Reply 165

can someone pls help me with q5 http://www.ocr.org.uk/Images/63190-question-paper-unit-4728-01-mechanics-1.pdf

Reply 166

OP

Original post by buckeybarnes

1.59m

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Reply 167

OP

Original post by buckeybarnes

can someone pls help me with q5 http://www.ocr.org.uk/Images/63190-question-paper-unit-4728-01-mechanics-1.pdf

All of it? :smile:

Reply 168

Original post by MsFahima

All of it? :smile:

yeah pls i dont get it :frown:

, and the end part of q4 i got wrong as well, using t=5 instead of t=4, could u explain why in the last part of 4 it's t=4 as well if it's not too much please :smile:

Reply 169

sykik

Original post by alexann95

When P is at rest, the only force acting on P is the weight. Hence the reaction force must be equal and opposite to the weight.
Does this make sense?

And angle?

Reply 170

OP

Original post by buckeybarnes

yeah pls i dont get it :frown:

, and the end part of q4 i got wrong as well, using t=5 instead of t=4, could u explain why in the last part of 4 it's t=4 as well if it's not too much please :smile:

D.w I'll get back to you in a few mins! :smile:

Reply 171

Original post by MsFahima

D.w I'll get back to you in a few mins! :smile:

thanks ! i just tend to generally get very confused and annoyed when i see velocity time graph questions, never really got the grasp of them

Reply 172

OP

Original post by buckeybarnes

thanks ! i just tend to generally get very confused and annoyed when i see velocity time graph questions, never really got the grasp of them

I'm struggling with Q5 ii) unfortunatley. For Q5)i) The area under the graph is the displacement so we can work that out easily. (3*20)/2 = 30.

I'll tag @kawehi to help you out. I'm sorry!

Reply 173

huh, this question has got me pretty stumped, it's question 3i on http://www.ocr.org.uk/Images/59970-question-paper-unit-4728-mechanics-1.pdf

apparently you use v^2=u^2+2as, and take u=5, v=0, a=9.8, and s=2.5, but i don't get that. Surely if the particle is projected into the air from a point of 2.5m the displacement is over 2.5m because it is projected into the air? on the ascent the acceleration would be -9.8ms^2, but on the descent it would be 9.8ms^2, so on the descent wouldn't the initial velocity be 0, instead of 5? it's confusing me, it's like it has used the acceleration on the descent but the displacement cant be right....?

EDIT wait nvm i went through the process and i was right the mark scheme was just being very weird

(edited 8 years ago)

Reply 174

Original post by MsFahima

I'm struggling with Q5 ii) unfortunatley. For Q5)i) The area under the graph is the displacement so we can work that out easily. (3*20)/2 = 30.

I'll tag @kawehi to help you out. I'm sorry!

thanks

Reply 175

OP

Original post by buckeybarnes

thanks

You're using t = 4 because when it comes to (instantaneous) rest after moving past O, t = 4.

Reply 176

Original post by MsFahima

You're using t = 4 because when it comes to (instantaneous) rest after moving past O, t = 4.

i got as far as thinking that the total time is 60+ the base of the trapezium next to 60, but i was unsure how to work out the area of the trapezium with only the information we were provided with :smile:

Reply 177

OP

Original post by buckeybarnes

i got as far as thinking that the total time is 60+ the base of the trapezium next to 60, but i was unsure how to work out the area of the trapezium with only the information we were provided with :smile:

I'm so confused! :frown:

Reply 178