A substance made up of only one type of element
Answer: µ=0.205
Explanation:
The horizontal forces acting on the ladder are the friction(f) at the floor and the normal force (Fw) at the wall. For horizontal equilibrium,
f=Fw
The sum of the moments about the base of the ladder Is 0
ΣM = 0 = Fw*L*sin74.3º - (25.8kg*(L/2) + 67.08kg*0.82L)*cos74.3º*9.8m/s²
Note that it doesn't matter WHAT the length of the ladder is -- it cancels.
Solve this for Fw.
0= 0.9637FwL - (67.91L)2.652
Fw=180.1/0.9637
Fw=186.87N
f=186.81N
Since Fw=f
We know Fw, so we know f.
But f = µ*Fn
where Fn is the normal force at the floor --
Fn = (25.8 + 67.08)kg * 9.8m/s² =
910.22N
so
µ = f / Fn
186.81/910.22
µ= 0.205
Answer:
The block has an acceleration of 
Explanation:
By means of Newton's second law it can be determine the acceleration of the block.
(1)
Where 
represents the net force, m is the mass and a is the acceleration.
(2)
The forces present in x are 
and 
(the friction force):
Notice that 
subtracts to 
since it is at the opposite direction.
The forces present in y balance each other:
Therefore:
(3)
But 
and writing (3) in terms of a it is get:
So the block has an acceleration of .
Answer:
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