请问这一步是怎么得到的,请写一下具体过程
1个回答
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左边
∫(t,0) dt/m
=t/m |(t,0)
=t/m
右边
∫(v,0) dv/(-kv+mg)
=(-1/k)∫(v,0) d(-kv+mg)/(-kv+mg)
=(-1/k)*ln(-kv+mg) |(v,0)
=-(1/k)[ln(-kv+mg)-ln(mg)]
=-(1/k)ln[(-kv+mg)/(mg)]
所以
t/m=-(1/k)ln[(-kv+mg)/(mg)]
-kt/m=ln[(-kv+mg)/(mg)]
e^(-kt/m)=(-kv+mg)/(mg)
mg*e^(-kt/m)=-kv+mg
mg*e^(-kt/m)-mg=-kv
mg[1-e^(-kt/m)]=kv
v=mg[1-e^(-kt/m)]/k
∫(t,0) dt/m
=t/m |(t,0)
=t/m
右边
∫(v,0) dv/(-kv+mg)
=(-1/k)∫(v,0) d(-kv+mg)/(-kv+mg)
=(-1/k)*ln(-kv+mg) |(v,0)
=-(1/k)[ln(-kv+mg)-ln(mg)]
=-(1/k)ln[(-kv+mg)/(mg)]
所以
t/m=-(1/k)ln[(-kv+mg)/(mg)]
-kt/m=ln[(-kv+mg)/(mg)]
e^(-kt/m)=(-kv+mg)/(mg)
mg*e^(-kt/m)=-kv+mg
mg*e^(-kt/m)-mg=-kv
mg[1-e^(-kt/m)]=kv
v=mg[1-e^(-kt/m)]/k
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