- #1
koonts
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Homework Statement
A 46.5 kg kid on roller blades pushes as hard as he can on a wall which causes him to start rolling away from the wall. At this point, friction begins to slow him down and he comes to rest 14.3 m from the wall. The coefficient of friction is 0.125. If his push lasted 0.460 s, how hard did he push on the wall (in Newtons)?
Rough diagram:
2. The attempt at a solution
J = Δ p
fΔt = mv2 - mv1 (mv2 = 0, since v2 is 0)
v1 = (Fft)/(-46.5)
v1 = -0.563 m/s **
Ff = μFn
=(0.125)(46.5)(9.8)
= 56.96N ( **I substituted this value to Ff in the (Fft)/(-46.5) equation to find v1)
a = v2 - v1 (v2 = 0)
t
a =0.5630.460
a= 1.225 m/s2Fnet = ma
= (46.5)(1.225)
= 56.96N
Therefore, the average force exerted on the wall is 56.96N(BKWD)?
I tried doing this problem today but I feel that the answer is wrong(doesn't make sense) and that I made a mistake. Any help would greatly be appreciated :tongue: