Author Topic: Edexcel PHYSICS Doubts  (Read 124934 times)

Offline Saladin

  • The Samurai
  • Honorary Member
  • SF V.I.P
  • *****
  • Posts: 6530
  • Reputation: 59719
  • Gender: Male
  • I believe in those who believe in me
    • Student Tech
Re: Edexcel PHYSICS Doubts
« Reply #150 on: July 31, 2010, 11:39:05 am »
Thank you very much sir. + REP :)

Offline Saladin

  • The Samurai
  • Honorary Member
  • SF V.I.P
  • *****
  • Posts: 6530
  • Reputation: 59719
  • Gender: Male
  • I believe in those who believe in me
    • Student Tech
Re: Edexcel PHYSICS Doubts
« Reply #151 on: August 02, 2010, 12:18:55 am »
Sir would you be kind enough to answer the questions 2(a) 2(b) and 5(c) in more detail please.

Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
Re: Edexcel PHYSICS Doubts
« Reply #152 on: August 02, 2010, 01:30:08 pm »
for  2a)if the ball hardly changes direction becuase the batman hots a glancing blow then then the momentum will hardly change. Inpulse =change in momentum so is small
b)Impulse=m(v-u)=m(-u--u)=-2mu becuase ball is hit right back to batsman
5c)rubber is better at absorbing energy than metal or wood.

Offline Saladin

  • The Samurai
  • Honorary Member
  • SF V.I.P
  • *****
  • Posts: 6530
  • Reputation: 59719
  • Gender: Male
  • I believe in those who believe in me
    • Student Tech
Re: Edexcel PHYSICS Doubts
« Reply #153 on: August 02, 2010, 06:30:06 pm »
for  2a)if the ball hardly changes direction becuase the batman hots a glancing blow then then the momentum will hardly change. Inpulse =change in momentum so is small
b)Impulse=m(v-u)=m(-u--u)=-2mu becuase ball is hit right back to batsman
5c)rubber is better at absorbing energy than metal or wood.

Thanks again! :D

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: Edexcel PHYSICS Doubts
« Reply #154 on: August 04, 2010, 03:59:54 pm »
Y is it B?

Cud someone explain with a diagram?
divine intervention!

Offline Saladin

  • The Samurai
  • Honorary Member
  • SF V.I.P
  • *****
  • Posts: 6530
  • Reputation: 59719
  • Gender: Male
  • I believe in those who believe in me
    • Student Tech
Re: Edexcel PHYSICS Doubts
« Reply #155 on: August 04, 2010, 04:39:40 pm »
Y is it B?

Cud someone explain with a diagram?

This is because the car is moving, and the reaction is opposite to the combined force of the car. Which is a diagonal force.

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: Edexcel PHYSICS Doubts
« Reply #156 on: August 05, 2010, 04:21:34 pm »
Thanks. This one too.

http://img94.imageshack.us/img94/7417/blahfu.png

Answer : 1.4m/s^2
divine intervention!

Offline Saladin

  • The Samurai
  • Honorary Member
  • SF V.I.P
  • *****
  • Posts: 6530
  • Reputation: 59719
  • Gender: Male
  • I believe in those who believe in me
    • Student Tech
Re: Edexcel PHYSICS Doubts
« Reply #157 on: August 05, 2010, 06:08:56 pm »
Thanks. This one too.

http://img94.imageshack.us/img94/7417/blahfu.png

Answer : 1.4m/s^2

LOL at the image name "Blahfu" :P

There are two forces acting here, the force of gravity acting on the block, and the force of friction, which is 6N.

The force pulling the weight down is, 2*9.81=19.62N

Therefore, the net force is, 19.62-6=13.62N

Now, when doing these calculations, there is uniform acceleration, because the acceleration of the 8 KG box is the same as the acceleration of the 2 KG box.

So, F=ma

13.62=(8+2)a

\frac{13.62}{10}=1.362

\approx1.4

nid404

  • Guest
Re: Edexcel PHYSICS Doubts
« Reply #158 on: August 06, 2010, 05:48:34 am »
Thanks. This one too.

http://img94.imageshack.us/img94/7417/blahfu.png

Answer : 1.4m/s^2

2g-T=2a
T-6=8a

solve simultaneously

14=10a
a=1.4m/s

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: Edexcel PHYSICS Doubts
« Reply #159 on: August 06, 2010, 04:27:37 pm »
Thanks dude, that is what i wanted.

@Nid - Cud u plz rite the steps abts solving the equations simultaneously with 3 variables. Thanks
divine intervention!

Offline cooldude

  • SF Citizen
  • ***
  • Posts: 172
  • Reputation: 3600
Re: Edexcel PHYSICS Doubts
« Reply #160 on: August 06, 2010, 04:30:48 pm »
Thanks dude, that is what i wanted.

@Nid - Cud u plz rite the steps abts solving the equations simultaneously with 3 variables. Thanks


dude, there arent three variables g is a constant, neway if u still want the working here it is-->

2g-T=2a
T-6=8a
T=2g-2a, and T=8a+6
8a+6=2g-2a
10a=2g-6
g=10
10a=20-6
10a=14
a=14/10=1.4

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: Edexcel PHYSICS Doubts
« Reply #161 on: August 06, 2010, 04:37:42 pm »
dude, there arent three variables g is a constant, neway if u still want the working here it is-->

2g-T=2a
T-6=8a
T=2g-2a, and T=8a+6
8a+6=2g-2a
10a=2g-6
g=10
10a=20-6
10a=14
a=14/10=1.4

ahh, terrible error.

Thanks mate and thanks nid.

divine intervention!

nid404

  • Guest
Re: Edexcel PHYSICS Doubts
« Reply #162 on: August 07, 2010, 05:22:56 am »
anytime  :)

Offline Saladin

  • The Samurai
  • Honorary Member
  • SF V.I.P
  • *****
  • Posts: 6530
  • Reputation: 59719
  • Gender: Male
  • I believe in those who believe in me
    • Student Tech
Re: Edexcel PHYSICS Doubts
« Reply #163 on: August 12, 2010, 08:12:05 pm »
Guys I need help with this Physics question. Please assist!

The questions are attached.

1) I got velocity as 0.03 ms-1

2) a) I got velocity as 0.19 ms-1
    b) I got force as 100N

3) I explained that The boy goes to the right of the boat, and according to Newton's third law, the boat exerts an equal and opposite force     moving away from the boy.

4) Confused about the calculations involved.

5) Please help on this as well, I will check my answers when someone has posted.

Offline M-H

  • SF Master
  • ******
  • Posts: 1404
  • Reputation: 65535
Re: Edexcel PHYSICS Doubts
« Reply #164 on: August 13, 2010, 01:33:20 pm »
i'll post soon