物理 2004 年 DSE、CE 選擇題（第 2 頁）

11.

Photograph of a mother pushing a baby in a push-chair

The photograph shows a baby sitting on a push-chair and her mother Amy is pushing the push-chair with a uniform velocity $v$ along the horizontal ground. Let $F$ = horizontal force exerted by Amy on the push-chair, and $m$ = total mass of the baby and the push-chair. Which of the following expressions denotes the average output power of Amy in pushing the push-chair ?

12.

Martha 2 m behind Eric, and Eric 1 m in front of a plane mirror

Eric stands $1$ m in front of a plane mirror. Martha stands $2$ m behind Eric as shown above. Find the distance between Eric and the image of Martha formed by the mirror.

13.

Photograph of a tree and its image on a calm water surface

The photograph shows the image of a tree formed by the surface of a pool of calm water. Which of the following phenomena explains the formation of the image ?

14.

An object is placed in front of a concave lens. Which of the following statements about the properties of the image formed by the lens must be correct ?

(1)The image is diminished.

(2)The image is virtual.

(3)The image distance is smaller than the focal length of the lens.

15.

Object O in front of a concave lens with three incident rays; F and F' are the foci

An object $O$ is placed in front of a concave lens. $F$ and $F'$ are the foci of the lens. Which of the following diagrams shows the refracted rays of the three incident rays and the image $I$ correctly ?

16.

Photograph of a watch with a lens positioned over the date-display

The photograph shows a watch with a lens positioned over the date-display. Which of the following statements are correct ?

(1)The lens is a convex lens.

(2)The image of the date-display formed by the lens is virtual.

(3)The date-display and its image lie on the same side of the lens.

17.

Temperature against time for substances P and Q heated separately from room temperature, each with a flat section

The graph shows the variation in temperature of equal masses of two substances $P$ and $Q$ when they are separately heated by identical heaters. Which of the following deductions is correct ?

18.

Questions 34 and 35 : The following set-up is used to measure $\ell_v$ , the specific latent heat of vaporization of a liquid.

Beaker of liquid with immersion heater connected to a kWh meter and power supply, standing on an electronic balance

The result of the experiment is as follows : Initial reading of the balance $= 1.60$ kg Final reading of the balance $= 1.45$ kg Energy supplied as measured by the kWh meter $= 0.10$ kWh Find the measured value of $\ell_v$ .

19.

Questions 34 and 35 : The following set-up is used to measure $\ell_v$ , the specific latent heat of vaporization of a liquid.

How will the value of $\ell_v$ obtained in the experiment be affected if the following measures are taken separately ? I. replacing the beaker with a polystyrene container which is a better insulator II. adding more liquid into the beaker until the heater is completely immersed

	I	II
	decreases	increases
	decreases	decreases
	increases	increases
	increases	decreases

20.

Waveform of a transverse stationary wave with P at its lowest position and Q on the equilibrium line

The figure shows the waveform of a transverse stationary wave at a certain instant. If particle $P$ is at its lowest position at this instant, what will be the instantaneous motion of particles $P$ and $Q$ after a quarter of a period ?

	$P$	$Q$
	moving upwards	at rest
	moving upwards	moving upwards
	at rest	at rest
	at rest	moving upwards