Solution:
1.m=3⋅105kg;
sinθ=0.128;
Fr=3000N;
a=0.2m/s2;
v=10m/s;
a) Fd=Fr+mgsinθ−ma;
Fd=3000N+300000kg⋅10N/kg⋅0.128−300000kg⋅0.2m/s2=327000N=327kN;
b)P=Fdv;
P=327000N⋅10m/s=3270000W=3.27MW;
c)W=Fscosϕ;
W=mgsinθscosϕ;
W=300000kg⋅10N/kg⋅0.128⋅(−1)=−384000J=
=384kJ;
2.m=54.4kg;
s=8.27m;
F=163N;
μ=0.227;
g=9.81m/s2;
a)W=Fscosϕ;
W=163N⋅8.27m⋅1=1348J=1.348kJ;
b)Wf=Ffscosϕ ;
Ff=μN=μmg;
Ff=0.227⋅54.4kg⋅9.81m/s2=121N;
Wf=121N⋅8.27m⋅(−1)=−1000J=−1kJ;
c)WN=Nscosϕ ;
N=mg;
WN=mgscosϕ;
WN=54.4kg⋅9.81m/s2⋅8.27m⋅0=0;
d) Wg=mgscosϕ;
Wg=54.4kg⋅9.81m/s2⋅8.27m⋅0=0;
Answer:1.a)Fd=327kN;
b)P=3.27MW;
c)W=381kJ;
2. a)W=1.348kJ;
b)Wf=−1kJ;
c)WN=0;
d)Wg=0;
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