Help required for M1

[Zazzyo]

I am aware there is a fomula a=g sin(x) where x is the angle to the horizontal of a slope and a is acceleration of particle sliding off the slope.

I am confused that in which cases is this formula used. is it valid when plane is rough? or when a external force acts upon the particle?

Can someone shed some light on what are the origins of this formula and how is it derived.

 

[Jurol]

hmmm, shouldn't it be mgsinx-F=ma if your talking about newtons law and forces.

when external forces act on the mass then it depends which way it is acting

1. motion of the object is up the slope : ExFor - mgsinx - F = ma
2.motion of the object is down the slope : ExFor +mgsinx - F = ma

theres another one, if the force is acting horizontal to the object, but for that u need to draw a diagram for your better understanding! its simple! xD I am not giving the paper this session . i wish i had :S

Jurol

 

[MAVtKnmJ]

Check my latest post!

 

[Zazzyo]

isnt it only a=gsin(thetha) ?? ive been getting the rite answers from it but do now know its details. and mg sin(x) is a force not acceleration MAVtKnm1. Oh i think its like this maybe...

Parallel component of weight(force F) is given by,

F=mgsin(x)

F/m=gsin(x)

since F/m is a. (newtons second law).. therefore..

a= gsin(x)

am i right?.. is this derivation correct?-

 

[mz23]

ok the derivation is correct...i just read in an examiner report that a=gsinx is to be used when an object slides down a smooth inclined plane

 

[MAVtKnmJ]

Always draw diagrams to help you better understand the question!
And it's...

mgsin(theta)-F=ma (for motion down the rough plane)
-mgsin(theta)-F=ma (for motion up the rough plane)

Note: F = Friction of the rough plane

mgsin(theta)=ma ----> gsin(theta)=a (for motion down a smooth plane)
-mgsin(theta)=ma ----> -gsin(theta)=a (for motion up a smooth plane)

The above formulas are used when something is moving up or down an inclined plane without any force (driving force or pulling force, not possible for up the slope movement but in AS mechanics we assume many things) acting upon it. For example a particle moving up the plane.

Hope that clears it up.