物理 1982 年 DSE、CE 選擇題

1.

Which of the following are vectors ?

(1)weight

(2)charge

(3)voltage

2.

A vehicle moving with uniform speed travels up a road of constant gradient. The power developed by the vehicle's engine is

3.

Which of the following statements concerning the energy of a body falling freely under the action of gravity is/are correct ?

(1)It gains kinetic energy while falling.

(2)Its total energy at any point in the flight is equal to the work done in raising it from ground level to that point.

(3)Its kinetic energy at the end of the flight is all converted into potential energy.

4.

A trolley on a smooth horizontal surface is pulled by two forces $P$ and $Q$ in the direction as shown in the figure. The magnitudes of $P$ and $Q$ are $2$ N and $1$ N respectively. If the mass of the trolley is $1$ kg, the acceleration of the trolley is

Trolley pulled by force P at 30 degrees above the horizontal to the right and force Q horizontally to the left

5.

Temperature-time graph: rises from 20 degrees C to 70 degrees C in 100 s, stays at 70 degrees C until 200 s, then rises again

A solid substance of mass $2$ kg and specific heat capacity $1000\ \mathrm{J\,kg^{-1}\,{}^\circ C^{-1}}$ is heated uniformly by a constant heat source. The temperature-time graph of the substance is shown in the graph. Assuming that no heat is lost, find from the graph the specific latent heat of fusion of the substance.

6.

A train of water waves is travelling from a deep water region to a shallow water region. Which of the following properties of the water waves will be changed ?

(1)wavelength

(2)frequency

(3)velocity

7.

A stationary wave is obtained by attaching one end of a string to a $50$ Hz vibrator as shown in the diagram. The velocity of the waves propagated in the string is

Stationary wave on a string between a vibrator and a fixed end, two loops spanning 0.1 m

8.

Arrange the following electromagnetic waves in descending order of their wavelengths :

(1)visible light

(2)X-rays

(3)radio waves

9.

Ray of light incident on a concave lens; F is the focus on each side

A ray of light is incident at a concave lens. $F$ is the focus of the lens. Which of the following diagrams correctly shows the path of the emergent ray ?

Four ray diagrams A to D for a concave lens

10.

A ray of light $I$ passes from a liquid $L$ into air makes an angle of incidence of $42^\circ$ . If the refractive index of the liquid $L$ is $1.35$ , the most probable emergent ray of light is

Ray I incident from the liquid on the air boundary at 42 degrees, with possible rays P, Q, R and S