How Do the Laws of Motion Apply to a Block and Wedge System?

[draotic]

Homework Statement

Given in the pic .. .

Homework Equations

F=mg

The Attempt at a Solution

i think block 2 hitting wedge will take place 1st as the direction of displacement of B1 is perpendicular to 'g' .. .
but i don't think that's a logical answer
please answer and explain why

 

[tiny-tim]

hi draotic!

call the displacement "x" and the angle "θ" …

what equations do you get? ​

 

[draotic]

sorry , i didnt quite get it .. .
which angle are we concerned about?

 

[tiny-tim]

the angle the right-hand part of the string makes with the horizontal at any particular time

 

[draotic]

well the angle will vary from 0 to pi/2 , so are we going to involve integration ?

 

[azizlwl]

Block#2 needs the highest force up at vertically down, weight plus centripetal force before continuing to hit the wedge.

Thus block#1 must hit the pulley first before bigger block can continue the circular motion.

 

[tiny-tim]

hi draotic!

(just got up :zzz:)

well the angle will vary from 0 to pi/2 , so are we going to involve integration ?

in problems like this, always try an energy equation first (which will avoid integration)

if that doesn't work, use a force equation (which will)

 

[draotic]

thanks tiny-tim and azizlwl for helping me out ..
azizlwl's reason seems quite right to me..
in B1 , only tension is involved ( ignoring kinetic friction ) and in B2 , we must have tension + centripetal force . .

so B1 must hit pulley first..

 

[draotic]

thanks tiny-tim and azizlwl for helping me out ..
azizlwl's reason seems quite right to me..
in B1 , only tension is involved ( ignoring kinetic friction ) and in B2 , we must have tension + centripetal force . .

so B1 must hit pulley first..

 

[nrbhyagrwl]

are all the parameters such as masses, distances from pulley variable?

 

[draotic]

are all the parameters such as masses, distances from pulley variable?

masses are same , no friction anywhere , no MI of pulley

 

[tiny-tim]

… no MI of pulley

you can assume the pulley is massless

(alternatively, just add its "rolling mass" (I/r²) to the mass of the first block)