Solve AS Level Statics- Mechanics Questions

In summary, the particle experiences a horizontal force of 19.6N and is moved up with a constant velocity.
  • #1
Beautiful Mess
39
0
This isn't a homework problem, I just have a general problem with solving AS level (M1) statics questions in mechanics that are similar to this example (our teacher have moved on to the next module now but I'm still stuggling with these):

example
A particle of mass 3kg rests in limiting equilibrium on a rough plane inclined at 30degrees to the horizontal. the coeffiecient of friction between the particle and the plane is 1/3. A horizontal force of magnitude XN is applied to the particle so that the equilibrium will be brocken by the particle moving upwards. Find the Value of X.

:confused: I always seem to get these wrong and i don't understand why. Here is how i wuld go about it, if anyone can tell me where and why my method is wrong please do! I really need to understand this soon. :frown:

attempt

Fr=1/3R
Fr=3g/sin30=58.8N
therefore R=58.8*1/3=19.6N

and there, this is where i get stuck and have absolutely no idea where to go from now. :cry:
 
Last edited:
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  • #2
Welcome to the forums Beautiful Mess,

Well, to begin with you've found the normal force and frictional force incorrectly. Have you drawn a free body diagram?
 
  • #3
Draw a free-body diagram and re-calculate the component of g along the incline.
 
  • #4
how do you calculate the component of g along an incline? (i feel really stupid)
our teacher never told us, she just expects us to work everything out ourselves.
I have a free body diagram, somehow it doesn't seem to help me at all. Ok I'm trying again:

does R=3gcos30 ?

and if so Fr would = (3gcos30)/3
 
  • #5
Beautiful Mess said:
does R=3gcos30 ?

and if so Fr would = (3gcos30)/3
That is correct! :approve: So now, this frictional force acts parallel to the incline (30o) to the horizontal. So what force is required to make this particle move with a constant velocity?
 
  • #6
yay i understood a little! :D

(ive also just noticed that the force X is applied at 30degrees to the plane)

so
Xcos30-Fr=R
Xcos30=3gcos30+(3gcos30/3)
X=all above/cos30

erm that looks wrong, i'll keep trying on paper
 
  • #7
oooh it doesn't = R it equals 0

and then perdendicular to plane

Xsin30 - R =0

so, no that must be wrong now i can get 2 different values for X...
 
  • #8
This is more a physics problem than math. I'm moving it to "homework-introductory physics"
 
  • #9
Beautiful Mess said:
(ive also just noticed that the force X is applied at 30degrees to the plane)

Your first post says the force is horizontal, this means that it will contribute to the normal force as well as the friction force
 
  • #10
HallsofIvy - I can see why you might class this as Physics but in England this is classed as a Module (Statics-Mechanics) of a Maths A level Course (pre-university qualification) and so we (British) would expect to find such questions under Mathematics (or Applied Mathematics) rather than physics.
 
  • #11
jing said:
HallsofIvy - I can see why you might class this as Physics but in England this is classed as a Module (Statics-Mechanics) of a Maths A level Course (pre-university qualification) and so we (British) would expect to find such questions under Mathematics (or Applied Mathematics) rather than physics.
Yea that's why I put it there, sorry.

Also I know my first post said horizontal but i mis-read it (i mixed it up with the question above). I seem to be understanding this better now though, so thank you for everyone's help :smile:
 
  • #12
I am officially a genious! not, but its amazing what a bag of marshmallows can help you learn! I get it now, its damn easy, I was such a fool not to see the way before! (ignore the way I'm speaking it sometimes happens when i have too much sugar...)
 

1. What is the purpose of solving AS Level Statics-Mechanics questions?

The purpose of solving AS Level Statics-Mechanics questions is to develop a strong understanding of the principles and laws related to statics and mechanics. This will help students apply these concepts to real-world problems and scenarios, as well as prepare them for further studies in engineering or physics.

2. What topics are covered in AS Level Statics-Mechanics questions?

The topics covered in AS Level Statics-Mechanics questions include vectors, forces, equilibrium, moments, and basic mechanics principles such as Newton's Laws of Motion, work, energy, and power.

3. How can I improve my problem-solving skills for AS Level Statics-Mechanics questions?

To improve your problem-solving skills for AS Level Statics-Mechanics questions, it is important to practice regularly and familiarize yourself with the fundamental concepts and formulas. You can also seek help from your teacher or tutor, and use online resources and practice problems to strengthen your skills.

4. How do I approach more complex AS Level Statics-Mechanics questions?

When tackling more complex AS Level Statics-Mechanics questions, it is important to first break down the problem into smaller, more manageable parts. Identify the given information, draw a diagram, and apply relevant concepts and formulas. Don't forget to check your final answer and make sure it makes sense in the context of the problem.

5. What are some common mistakes to avoid when solving AS Level Statics-Mechanics questions?

Some common mistakes to avoid when solving AS Level Statics-Mechanics questions include not reading the question carefully, using incorrect units, and not showing all the necessary steps in your solution. It is also important to double-check your calculations and make sure you understand the underlying principles behind the problem.

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