1electron chuyển động dọc theo đường sức của 1điện trường đều cường độ điện trường E=100 (v/m) vận tốc ban đầu bằng 300 (km/s) khối lượng electron là m=9,1*10-³¹(kg) . từ lúc bắt đầu chuyển động đến lúc vận tốc electron bằng 0 thì electron chuyển động được quảng đường bao nhiêu

1 câu trả lời

\(\left\{ \begin{array}{l}E=100V/m\\q=-1,6.10^{-19}C\\v_o=300km/s=3.10^5m/s\\m=9,1.10^{-31}kg\\v=0\\s=...m\end{array} \right.\) 

Ta có: $F=qE$

Mặc khác theo định luật II Niu-tơn $F=ma$

$⇒F=qE=ma$

$⇒a=\dfrac{qE}{m}=\dfrac{-1,6.10^{-19}.100}{9,1.10^{-31}}=-1,76.10^{13}m/s^2$

Quãng đường mà electron dịch chuyển

$v^2-v_o^2=2as$

$⇒s=\dfrac{v^2-v_o^2}{2a}=\dfrac{0-(3.10^5)^2}{2.-1,76.10^{13}}≈2,56.10^{-3}m$

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