Pare 2
foskr
[60 mak]
ishars
\[
\begin{array}{c}
\text { Pasi I } \\
\text { fis markey }
\end{array}
\]
All questions compr equat mark \( T \), in the string asd the linear density fi, by the formuls,
\[
f=\frac{1}{21} \sqrt{\frac{T}{p}}
\]
Obtain the basic units of fusing dimensional analysis.
[3 markol
(a) Name the two forces that act on the salelite.
(b) Sbow that the velocity, \( v \), of the satellie is related io \( h \) by the expression
\[
v a \frac{1}{\sqrt{R}}
\]
(3 marks)
3. A force of \( 50 \mathrm{pN} \) is required io stretch a sample of DNA strand of lengith \( 50 \mathrm{~nm} \) by \( 10 \% \) of its original length. Deiermine the cross-sectional area of the DNA strand. ['Young's Modulus, \( \mathrm{E}=1.0 \times 10^{6} \mathrm{~N} \mathrm{~m}^{-2} \) ]
[3 marks]
4. (a) A ball projected vertically opwards reached a maximum height of \( 356 \mathrm{~m} \) before returning to the level of projection. Caleulate the velocity of projection.
\[
\left[\mathrm{e}=10 \mathrm{~m} \mathrm{~s}^{2}\right]
\]
(b) Stale two factors that affect projectile motions
[3 marks]
5. The following elements were compared at low temperatures. Copy and complete the table.
\begin{tabular}{|l|l|l|l|}
\hline & Insulatars & Semicanductars & Melabs \\
\hline \begin{tabular}{l}
Location of \\
electrons
\end{tabular} & & & \\
\hline \begin{tabular}{l}
Width of \\
forbidden gap
\end{tabular} & & & \\
\hline
\end{tabular}
6. (a) Staie iwe applications of optical fibres
[3 marks]
(b) Exptain why the core of an opticat fitre is made very thin:
(3 marks)
7. State three applications of ferromagnetat materats
". mant
