物理 1995 年 DSE、CE 選擇題（第 2 頁）

11.

Block resting on the ground with forces R, W and F marked, and the meaning of W, F and R

The above diagram shows a block resting on the ground. Which of the following pairs of forces is/are action and reaction pair(s) according to Newton's third law of motion ?

(1)

R

and

W

(2)

W

and

F

(3)

F

and

R

12.

A convex lens is used as a magnifying glass to read some small print in a book. The glass is placed $3$ cm from the book and the magnification is $3$ . What is the distance between the book and the image of the print ?

13.

Convex lens with foci F and F', incident ray AB and possible emergent rays P, Q, R and S

In the above diagram, $F$ , $F'$ are the foci of the convex lens and $AB$ is an incident ray. Which of the following paths best represents the emergent ray ?

14.

Which of the following statements about heat is/are true ?

(1)Heat is used to describe the total energy stored in a body.

(2)Heat is used to describe the energy transferred from one body to another as a result of a temperature difference between them.

(3)A body's internal energy is increased when it is heated.

15.

Which of the following substances is a liquid at room temperature (about $20^\circ\mathrm{C}$ ) ?

Substance	Melting point / $^\circ$ C	Boiling point / $^\circ$ C
$P$	25	444
$Q$	$-39$	357
$R$	44	280
$S$	$-218$	$-183$

16.

Syringe with piston containing gas connected by rubber tubing to a Bourdon gauge

The above apparatus is used to study the relationship between the pressure and volume of a fixed mass of gas at constant temperature. Which of the following can improve the accuracy of the experiment ?

(1)Pressing the piston quickly.

(2)Using a large syringe.

(3)Using a short length of rubber tubing.

17.

The graph shows the result obtained when an experiment is performed to study Boyle's Law. What do the axes of the graph represent ?

Graph of y against x with experimental points (crosses) lying on a straight line rising from the origin

	$y$ axis	$x$ axis
	Volume	Temperature
	Volume	1 / Temperature
	Pressure	Volume
	Pressure	1 / Volume

18.

The melting point of copper is $1080^\circ\mathrm{C}$ and its specific latent heat of fusion is $2.1\times10^5\ \mathrm{J\,kg^{-1}}$ . How much energy is needed to melt $0.5$ kg of copper at its melting point ?

19.

A fixed mass of gas is heated at a constant pressure. Which of the following statements is/are correct ?

(1)The average speed of the gas molecules increases.

(2)The average spacing between the gas molecules increases.

(3)The number of gas molecules remains unchanged.

20.

A train of water waves is generated in a ripple tank. The graph below shows the variation of the displacement of a cork placed in the water with time. Find the frequency of the waves.

Displacement (cm) against time (s) graph, amplitude 0.25 cm, period 0.2 s