m1 help please!

A book of mass 2kg rests on a rough plane inclined at an angle theta to the horizontal. Given that cooefficient of friction is 0.2, and the book is on the point of slipping down the plane, find, to the nearest degree the value of theta?????

the answer is 11 degrees .....can someone help please

Reply 1

qwerty3

6

ok you know that F=mew R is going down the plane and that the frictional force is going up so you make the 2 force equal one another.
that should get you on the right path.

Reply 2

prash_s90

OP

16

i did that, but i ended up with :

F= MU R

2gsintheta - 2a = 0.2(2gcostheta)

im not o sure what to do after that ???

Reply 3

steve2005

17

prash_s90

A book of mass 2kg rests on a rough plane inclined at an angle theta to the horizontal. Given that cooefficient of friction is 0.2, and the book is on the point of slipping down the plane, find, to the nearest degree the value of theta?????

the answer is 11 degrees .....can someone help please

Here is a diagram that might help... now resolve

Picture 104.png9.6KB

Reply 4

qwerty3

6

prash_s90

i did that, but i ended up with :

F= MU R

2gsintheta - 2a = 0.2(2gcostheta)

im not o sure what to do after that ???

where did you get the 2a from ??
that bits wrong
hope you get it

Reply 5

steve2005

17

prash_s90

A book of mass 2kg rests on a rough plane inclined at an angle theta to the horizontal. Given that cooefficient of friction is 0.2, and the book is on the point of slipping down the plane, find, to the nearest degree the value of theta?????

the answer is 11 degrees .....can someone help please

Here, for a short time. I'm not keen on people that ask a question and then go off-line. i shall probably remove my attachement a bit later this evening.

Picture 105.png38.4KB

Reply 6

prash_s90

OP

16

ok this is what ive done so far:

R = 2gcostheta

2gsintheta-f +2a
f=2gsintheta-2a
F=MU R

2gsintheta-2a = 0.2( 2gcostheta)

im not sure how to find theta after that....any help appreciated

Reply 7

steve2005

17

prash_s90

ok this is what ive done so far:

R = 2gcostheta

2gsintheta-f +2a
f=2gsintheta-2a
F=MU R

2gsintheta-2a = 0.2( 2gcostheta)

im not sure how to fing theta after that....any help appreciated