physics question

[hassam]

http://xtremepapers.com/CIE/Internation ... 3_qp_4.pdf
q1 part b....i have learntt that centripetal force is not a force on its own bt rather a resultant force whic keeps object in circular path......so Fg can be providing it or Tension.....anything and its magnitude wud be equal to these sources which ll be providing it.....bt in this question i see a starnge unusual case and thus i dont understand how i shud anser last part of part B

 

[destined007]

Yes centripetal force is provided by gravitational force but only some part of GF is CF. Rest is the weight of the mass.
Gravitational force= centripetal force + weight

 

[hassam]

.....how u define weight ............Force of gravity acting on an object ....so i mean Fg is weight....i m cnfused

 

[destined007]

The gravity of Earth refers to the acceleration that the Earth causes to an objects on or near its surface.
Now here is the problem. Objects that are on the earth tends to go in a straight line. Place an eraser on your fist and rotate your fist quickly. You will notice that eraser will not remain stuck on your hand and will go in a straight line just as it leaves your hand. Same thing happens with the objects on Earth. There has to something to keep them in circular motion, in synchrony with earths rotation. So gravity comes in play and used some of itself to keep the object in the circular rotation. The left over gravity is your weight.

 

[hassam]

thanx buddy....

 

[destined007]

welcome.