Answer :
The work done by the friction force on the 8-kg sled is 64 Joule.
The work done by a force on an object is given by:
W = F . s
Where:
F = force
s = distance
Using the equation of motion:
v² = u² - 2 as
where:
v = final speed
u = initial velocity
a = acceleration
In this case v = 0 since the sled finally stops.
Hence,
0 = 4² - 2 as
2 as = 16
as = 8
Using the Newton's 2nd law of motion:
F = m . a
Where:
m = mass of the sled = 8
Substitute F = m . a into the work equation:
W = m . as
Substitute m = 8 and as = 8,
W = 8 x 8 = 64 Joule
Hence, the amount of work done is 64 Joule.
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