Question

Giúp mình giải mấy câu này với

Answer 1

Câu 68)

\(a,W=W_d+W_t=18J\\ b,W_t=2W_d\\ \Leftrightarrow1.10.h'=2.\dfrac{1.3^2}{2}\\ \Leftrightarrow h'=0,9m\) 

Câu 69)

\(a,W_d=4W_t\\ \Leftrightarrow\dfrac{0,4.30^2}{2}=4.0,4.10.z\\ \Leftrightarrow z=11,25m\\ b,W_d=8W_t\\ \Leftrightarrow\dfrac{0,4.v^2}{2}=8.0,4.10.11,25\\ \Leftrightarrow v\approx42m/s\\ c,W_d=W_t\\\Leftrightarrow180=0,4.10.hmax\Leftrightarrow hmax=45m\) 

Câu 70)

\(W_d=W_t\\ \Leftrightarrow\dfrac{0,2.20^2}{2}=0,2.10.hmax\Leftrightarrow hmax=20m\)

Answer 2

Câu 71)

\(W_d=3W_t\\ \Leftrightarrow1,2=3.0,15.10.h'\Leftrightarrow h'=0,2\left(6\right)m\)

Câu 72)

\(W_d=\dfrac{mv^2}{2}=\dfrac{0,5.\left(\sqrt{\dfrac{2.50}{10}}.10\right)^2}{2}=1250J\)