Newtons third law of motion

  • Thread starter ecy5maa
  • Start date
  • #1
ecy5maa
30
0

Homework Statement



A particle of mass 4kg is being towed at a constant speed up a rough plane inclined at 30 degrees to the horizontal by a force 4g N acting parallel to the slope. At the top of the slope the particle moves onto a rough horizontal slope with the same coefficient of friction. If the towing force continues to act in the same direction, show that the particle undergoes an acceleration of

[tex]\frac{g\sqrt{3}}{6}[/tex] m.second square

Homework Equations



basically use F=ma and get the answer where m=4kg

The Attempt at a Solution



1. On the inclined plane coefficient of friction was calculated as 1/ (sqrt 3)

2.Since they say the force of 4g will be acting in the same direction even when it is on the horizontal plane i took this too mean that 4g will be acting at an angle 30 degrees to the horizontal when the particle is on a horizontal plane..

This way Reaction force would be 4g-4gsin30= 2g

And net force would be equal too

4a= 4gcos30 - 2g/ (sqrt 3)


which makes a = [tex]\frac{g\sqrt{3}}{3}[/tex] m.second square which is twice the answer that is given.


Can some one please check this out. Its from an A level Mechanics book
 

Answers and Replies

  • #2
collinsmark
Homework Helper
Gold Member
3,169
1,930
For what it's worth, I also ended up with your answer that [tex] a = g\sqrt{3}/3 [/tex]
 
  • #3
SammyS
Staff Emeritus
Science Advisor
Homework Helper
Gold Member
11,600
1,187

Homework Statement



A particle of mass 4kg is being towed at a constant speed up a rough plane inclined at 30 degrees to the horizontal by a force 4g N acting parallel to the slope. At the top of the slope the particle moves onto a rough horizontal slope with the same coefficient of friction. If the towing force continues to act in the same direction, show that the particle undergoes an acceleration of

[tex]\frac{g\sqrt{3}}{6}[/tex] m.second square

Homework Equations



basically use F=ma and get the answer where m=4kg

The Attempt at a Solution



1. On the inclined plane coefficient of friction was calculated as 1/ (sqrt 3)


Can some one please check this out. Its from an A level Mechanics book

Show how you calculate the coefficient of friction, μ.

I get, [tex]\mu=\frac{2}{\sqrt{3}}\,.[/tex]

Added in an edit. Ignore this post!
 
Last edited:
  • #4
collinsmark
Homework Helper
Gold Member
3,169
1,930

Show how you calculate the coefficient of friction, μ.

I get, [tex]\mu=\frac{2}{\sqrt{3}}\,.[/tex]
I ended up with μ = 1/√3, which agrees with the original poster. (The pulling force must be equal in magnitude to the frictional force plus the component of gravitational force parallel to the slope.) But I'll let ecy5maa comment further.
 
  • #5
SammyS
Staff Emeritus
Science Advisor
Homework Helper
Gold Member
11,600
1,187
I ended up with μ = 1/√3, which agrees with the original poster. (The pulling force must be equal in magnitude to the frictional force plus the component of gravitational force parallel to the slope.) But I'll let ecy5maa comment further.

I agree.

μ = 1/√3
 

Suggested for: Newtons third law of motion

  • Last Post
Replies
3
Views
3K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
2
Views
766
  • Last Post
Replies
9
Views
3K
  • Last Post
Replies
2
Views
3K
  • Last Post
Replies
13
Views
3K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
3
Views
6K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
1
Views
3K
Top