A force of 25N acting on a body of mass 100kg produces uniform velocity if the force is doubled then acceleration produced will become
Answers
Answered by
2
got:
μ
s
=
0.51
F
=
78.4
N
Explanation:
At the start the
100
N
force is just enough to overcome static friction so we can write:
Force
=
Static Friction
F
=
μ
s
N
where
μ
s
is the coefficient of static friction and
N
=
Normal Reaction that in an horizontal case such this will be equal to the weight of the block, so
N
=
m
g
.
We get:
F
=
μ
s
⋅
m
g
in numbers:
100
=
μ
s
⋅
20
⋅
9.8
μ
s
=
100
20
⋅
9.8
=
0.51
When the movement starts, kinetic friction kicks in and we have that to have uniform motion we need acceleration equal to zero (constant velocity).
We use Newton's Second Law:
Σ
→
F
=
m
→
a
or in our case:
Force
−
Kinetic Friction
=
mass
⋅
acceleration
or
F
−
μ
k
N
=
0
because acceleration has to be zero.
F
−
μ
k
⋅
m
g
=
0
in numbers:
F
−
0.4
⋅
20
⋅
9.8
=
0
F
=
78.4
N
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