Ответ: 2,4 13 Небольшой предмет расположен на главной оптической оси тонкой собираюшей линзы с фокусным расстоянием 20 cm . Расстояние от линзы до предмета составляет 40 cm . Определите расстояние от линзы до изображения предмета. Ответ:

10. Hajmi \( 50 \mathrm{~cm}^{3} \) bo lgan alyumin sharning massasi 135 g . Agar \( 1 \mathrm{cmm}^{3} \) alyuminning massasi \( 1 \mathrm{~cm}^{3} \) temiming massasidan \( 5,2 \mathrm{~g} \) kam bo'lsa, shunday hajmdagi temir sharning massasi qancha bo ladi?

6. A particle undergoes three consecutive displacements: \( \bar{d}_{1}=(15 i+30 j+12 k) \mathrm{cm} \). \( \vec{d}_{2}=(23 i-14 j-5 k) a n \) and \( \vec{d}_{3}=(-13 i+15 j) \) an Find the magnitude of the resultant displacement.

14 If velocity, momentum and kinetic energy of a particle are represented by \( v, p \) and \( k \) respectively then, which relation is correct ? \( \begin{array}{ll}\text { (1) } p=\frac{d k}{d v} & \text { (2) } p=\frac{d k}{d t} \\ \text { (3) } p=\frac{d v}{d t} & \text { (4) } p=\left(\frac{d k}{d v}\right)\left(\frac{d k}{d t}\right) \\ \text { यदि } \nu, p \text { और } k \text { क्रमशः कण के वेग, संवेग और गतिज ऊर्जा हैं तो निम्न में से } \\ \text { कौन-सा सम्बन्ध सही है ? } \\ \begin{array}{ll}\text { (1) } p=\frac{d k}{d v} & \text { (2) } p=\frac{d k}{d t}\end{array}\end{array} \).

A bullet of mass 120 grams is fired into a target of mass 10 kg with velocity \( 400 \mathrm{~m} / \mathrm{s} \). If the target is free to move, the loss of kinetic energy would be approximately \( \begin{array}{ll}\text { (1) } 9.5 \mathrm{kNm} & \text { (2) } 4.75 \mathrm{kNm} \\ \text { (3) } 19 \mathrm{kNm} & \text { (4) } 0\end{array} \)

? (What is free fall?) (What is gravity?)