MedPR

Membership Revoked
Removed
Dec 1, 2011
18,579
52
Status (Visible)
  1. Pre-Podiatry
Question 1: Why/how do you know that theta between the incline and the horizontal is the same as theta between the mg vector and the mgcostheta vector?

Edit:

Might as well ask this question here too.

Question 2: When asked to find the equation that represents the acceleration of a package sliding down a frictionless inclined plane that makes an angle theta with the horizontal ground, will this method always work?

Fnet = mg + Fnormal.

Since mg = mgcostheta + mgsintheta

Fnet = mgcostheta+mgsintheta+Fnormal

And since Fnormal and mgcostheta cancel each other out,

Fnet = mgsintheta = ma

so a = gsintheta

Question 3: And if a=gsintheta, then the force acting on the package down the incline is F=mgsintheta?

I'm sure this is basic inclined plane derivation, but I haven't been in Physics for a few years, and I'm realizing now that I might not have learned it (even though we were required to).

Thank you!
 
Last edited:

Pisiform

Oh Crap!!!
10+ Year Member
Nov 27, 2009
1,182
369
La La Land
Status (Visible)
  1. Resident [Any Field]
Question 1: Why/how do you know that theta between the incline and the horizontal is the same as theta between the mg vector and the mgcostheta vector?

Try this if it works ... its all about angles:

Jwq0g.jpg


Edit:

Might as well ask this question here too.

Question 2: When asked to find the equation that represents the acceleration of a package sliding down a frictionless inclined plane that makes an angle theta with the horizontal ground, will this method always work?

Fnet = mg + Fnormal.

Since mg = mgcostheta + mgsintheta

Fnet = mgcostheta+mgsintheta+Fnormal

And since Fnormal and mgcostheta cancel each other out,

Fnet = mgsintheta = ma

so a = gsintheta

yes and also when no rope Tension) attached to the object

Question 3: And if a=gsintheta, then the force acting on the package down the incline is F=mgsintheta?


Yes
 

study pray love

Full Member
Apr 15, 2011
139
1
Status (Visible)
  1. Pre-Medical
alternative way to look at it:
assuming the incline is frictionless

in the x direction:
Fnet= Fapplied- Fresisting= ma
so
Fnet= parallel force- 0= ma
Fnet=mgsintheta= ma

so Fnet= mgsintheta and gsintheta=a
 
This thread is more than 9 years old.

Your message may be considered spam for the following reasons:

  1. Your new thread title is very short, and likely is unhelpful.
  2. Your reply is very short and likely does not add anything to the thread.
  3. Your reply is very long and likely does not add anything to the thread.
  4. It is very likely that it does not need any further discussion and thus bumping it serves no purpose.
  5. Your message is mostly quotes or spoilers.
  6. Your reply has occurred very quickly after a previous reply and likely does not add anything to the thread.
  7. This thread is locked.