Author Topic: help help in M1  (Read 1196 times)

Offline T.Q

  • SF Master
  • ******
  • Posts: 1557
  • Reputation: 5081
  • Gender: Male
help help in M1
« on: December 13, 2009, 09:46:31 pm »
A post is driven into the ground by means of a blow from a pile-driver. The pile-driver falls
from rest from a height of 1.6 m above the top of the post.

(a) Show that the speed of the pile-driver just before it hits the post is 5.6 m s–1. (2 marks)

The post has mass 6 kg and the pile-driver has mass 78 kg. When the pile-driver hits the top
of the post, it is assumed that the there is no rebound and that both then move together with
the same speed.

(b) Find the speed of the pile-driver and the post immediately after the pile-driver has hit the
post. (3 marks)

The post is brought to rest by the action of a resistive force from the ground acting for 0.06 s. By modelling this force as constant throughout this time,

(c) find the magnitude of the resistive force, (4 marks)

(d) find, to 2 significant figures, the distance travelled by the post and the pile-driver before
they come to rest.(4 marks)

i need help in part C

By the way in the mark scheme the answer is F = 8103.2 N
i need to know the way we solve this question plz help

No Matter What Happens In Life , Just Don't Lose Hope :)

Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
Re: help help in M1
« Reply #1 on: December 14, 2009, 08:29:31 am »
When i get up

Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
Re: help help in M1
« Reply #2 on: December 14, 2009, 10:39:18 am »
check this

Offline sweetest angel

  • Oh dear beach I await...
  • SF Geek
  • ****
  • Posts: 346
  • Reputation: 259
  • Gender: Female
Re: help help in M1
« Reply #3 on: December 14, 2009, 05:23:56 pm »
8103.2N is the answer in the markscheme
i did it YAY!
 astar used f=ma
                f=84x86.7
                f = 7282.8
 
i tried       F-84g=84x260/3
               F= 8103.2N
"Dont fear the creation, but fear the creator who has created the creation you fear"
"If you educate a man, you educate an individual, but if you educate a female, you educate a nation"
 I DO WHAT I WANT WHERE I WANT WHEN I WANT if mom says ok.

Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
Re: help help in M1
« Reply #4 on: December 14, 2009, 05:59:57 pm »
How did i forget gravity

Offline sweetest angel

  • Oh dear beach I await...
  • SF Geek
  • ****
  • Posts: 346
  • Reputation: 259
  • Gender: Female
Re: help help in M1
« Reply #5 on: December 14, 2009, 06:33:08 pm »
"Dont fear the creation, but fear the creator who has created the creation you fear"
"If you educate a man, you educate an individual, but if you educate a female, you educate a nation"
 I DO WHAT I WANT WHERE I WANT WHEN I WANT if mom says ok.

Offline T.Q

  • SF Master
  • ******
  • Posts: 1557
  • Reputation: 5081
  • Gender: Male
Re: help help in M1
« Reply #6 on: December 14, 2009, 07:33:49 pm »
thanx :)
No Matter What Happens In Life , Just Don't Lose Hope :)