Tóm tắt :
\(m=2tấn=2000kg\)
\(v=10m/s\)
\(P=40kW=40000W\)
\(g=10m/s^2\)
\(\mu\) =?
GIẢI :
\(\overrightarrow{N}+\overrightarrow{P}=\overrightarrow{0}\)
=> \(N=P=mg=20000\left(N\right)\)
\(F=\frac{P}{v}=\frac{40000}{10}=4000\left(N\right)\)
=> \(F_{ms}=P-F=16000N\)
mà : \(F_{ms}=\mu.N\)
=> \(\mu=\frac{F_{ms}}{N}=0,8\)