Elastisitas

Jawaban: E

Rumus energi potensial pegas adalah:

\(\text{Ep} = \dfrac{1}{2}\text{k}\triangle \text{x}^2\)

\(\text{Ep} = \dfrac{1}{2}\text{A}\triangle \text{B}^2\)

Jawaban: D

Rumus modulus Young kawat:

\(\color{blue}\text{E} = \dfrac{\text{F}\cdot l_0}{\text{A}\cdot \triangle l}\)

\(2 \times 10^{11} = \dfrac{\text{m.g}\cdot 5}{0,2 \times 10^{-4}\cdot \triangle l}\)

\(2 \times 10^{11} = \dfrac{3000\cdot 5}{0,2 \times 10^{-4}\cdot \triangle l}\)

\(2 \times 10^{11} = \dfrac{15000}{0,2 \times 10^{-4}\cdot \triangle l}\)

\(2\times 10^{11}\times 0,2 \times 10^{-4} \cdot \triangle l = 1,5 \times 10^4 \)

\(4 \times 10^6 \cdot \triangle l = 1,5 \times 10^4 \)

\(\triangle l = \dfrac{1,5 \times 10^4}{4 \times 10^6} \)

\(\triangle l = 3,75 \times 10^{-3} \text{ m}\)

\(\triangle l = 37,5 \times 10^{-2}\) cm

Jawaban: A

Langkah 1: menghitung konstanta pegas

\(\text{Ep} = \dfrac{1}{2}\text{k}\triangle \text{x}^2\)

\(0,48 = \dfrac{1}{2}\text{k}\times (4 \times 10^{-2})^2\)

\(0,48= \text{k}\times 8\times 10^{-4}\)

\(\text{k} = \dfrac{0,48}{8\times 10^{-4}}\)

\(\text{k} = 600 \text{ N/m}\)

Langkah 2: menghitung \(\triangle x_3\)

Dari soal diketahui bahwa \(\text{F}_3 = 18 \text{ N}\)

\(\text{F}_3 = \text{k} \cdot \triangle x_3\)

\(18 = 600 \cdot \triangle x_3\)

\(\triangle x_3 = \dfrac{18}{600}\)

\(\triangle x_3 = 0,03 \text{ m}\)

\(\triangle x_3 = 3 \text{ cm}\)

Langkah 3: menghitung besar gaya F1

\(\triangle x_3 \:-\: \triangle x_1 = 2 \text{ cm}\)

\(3 \text{ cm}\:-\: \triangle x_1 = 2 \text{ cm}\)

\(\triangle x_1 = 1 \text{ cm}\)

\(\triangle x_1 = 1 \times 10^{-2} \text{ m}\)

\(\text{F}_1 = \text{k} \cdot \triangle x_1\)

\(\text{F}_1 = 600 \cdot 1 \times 10^{-2}\)

\(\text{F}_1 = 6 \text{ N}\)