- #1
MisterOL
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Homework Statement
2 blocks are connected with wire each on its own angle area. Body 1 (B1) has weight 900N, angle 30, µ = 0,35
B2 wight = 1100N, angle 45 and µ=0.30
There is no friction on at the T ( picture )
How big F has to be to pull block1 down following shown path?
Homework Equations
SUM FY=0
SUM Fx=0
Ff = µ * N
The Attempt at a Solution
I separated system and tok a look at block 2
- since there is 45 degrees angle between G2x and G2y they have to be same in size ( 1110 / 2 = 550 N )
- Since N2 = G2y, N2 is 550N as well. (Sum Fy=0)
- Since the point is to glide block nr 1 down that means that bloock 2 has to go up hence Friction force (F2) poiniting down or along the 45 degres plate
- If Ff = µ * N that means Ff2 = 0.30 x 550 which is 165
- Since G2x and FF2 pointing in the same direction (Sum Fx=0) there has to be an F force that pulls block 2 towards T and it is F2 = Ff2 + G2x which is 165 + 550 = 715 N
Now back to block 1
G1x = G * sin30 = 900 * sin30 = 450 N
G1y = G * cos30 = 779,42 N
N1 = 779, 42 N
Ff1 = 0,35 * 779,42 = 272,78 N
Sum Fx = 0 gives
+ Ff1 - F - G1x = 0 => F= Ff1-G1x => 272,78 - 450 = -177,22
This also means that F2 force from block 2 makes somehow impact.
The correct answer is F = 834 N and I have tried different aproaches but no luck .
Can someone that understand this perticular part please take a look at this problem ?
Help appritiated :)