*2. 1. Which of the following pairs of units are both SI base units?
A、ampere, degree celsius
B、ampere, kelvin
C、coulomb, degree celsius
D、coulomb, kelvin
查看答案
*3. 2. A micrometer screw gauge is used to measure the diameter of a copper wire.The reading with the wire in position is shown in diagram 1. The wire is removed and the jaws of the micrometer are closed. The new reading is shown in diagram 2.
What is the diameter of the wire?
A、1.90 mm
B、2.45 mm
C、2.59 mm
D、2.73mm
查看答案
*4. 3. A projectile is launched at point O and follows the path OPQRS, as shown. Air resistance may be neglected.
Which statement is true for the projectile when it is at the highest point Q of its path?
A、The horizontal component of the projectile’s acceleration is zero.
B、The horizontal component of the projectile’s velocity is zero.
C、The kinetic energy of the projectile is zero.
D、The momentum of the projectile is zero.
查看答案
*5. 单行填空
*6. 4. A wooden block of mass 0.60 kg is on a rough horizontal surface. A force of 12 N is applied to the block and it accelerates at 4.0ms–2.
What is the magnitude of the frictional force acting on the block?
A、2.4 N
B、9.6 N
C、14N
D、16 N
查看答案
*7. 5. A pendulum bob is held stationary by a horizontal force H. The three forces acting on the bob areshown in the diagram.
The tension in the string of the pendulum is T. The weight of the pendulum bob is W. Which statement is correct?
查看答案
*8. 6. A car driver adjusts the pressure on a car’s brakes so that the car travels at constant speed down a hill from P to Q.The magnitude of the change in the car’s kinetic energy is ΔEk. The magnitude of the change in its gravitational potential energy is ΔEp.Which statement is correct?
查看答案
*9. 7. A child drinks a liquid of density ρ through a vertical straw.[Work,Energy, Power]Atmospheric pressure is p0 and the child is capable of lowering the pressure at the top of the straw by 10%. The acceleration of free fall is g.What is the maximum length of straw that would enable the child to drink the liquid?
查看答案
*10. 8. The four graphs represent a progressive wave on a stretched string. Graphs A and B show how the displacement d varies with distance x along the string at one instant. Graphs C and D show how the displacement d varies with time t at a particular value of x.The labels on the graphs are intended to show the wavelength λ, the period T, and the amplitude a of the wave, but only one graph is correctly labelled.Which graph is correctly labelled?
查看答案
*11. 9. Coherent monochromatic light illuminates two narrow parallel slits and the interference pattern that results is observed on a screen some distance beyond the slits.Which change increases the separation between the dark lines of the interference pattern?
A、using monochromatic light of higher frequency
B、using monochromatic light of a longer wavelength
C、decreasing the distance between the screen and the slits
D、increasing the distance between the slits
查看答案
*12. 10. Two parallel conducting plates are connected to a battery, one plate to the positive terminal and the other plate to the negative. The plate separation is gradually increased, the plates remaining connected to the battery.Which graph shows how the electric field E between the plates depends on the plate separation x ?
查看答案
*13. 11. The filament of a 240 V, 100W electric lamp heats up from room temperature to its operating temperature. As it heats up, its resistance increases by a factor of 16. What is the resistance of this lamp at room temperature?
查看答案
*14. 12. The graph shows how the current through a lamp filament varies with the potential difference across it.
Which statement explains the shape of this graph?
A、As the filament temperature rises, electrons can pass more easily through the filament.
B、It takes time for the filament to reach its working temperature.
C、The power output of the filament is proportional to the square of the current through it.
D、The resistance of the filament increases with a rise in temperature.
查看答案
*15. 13. Which set of radioactive emissions corresponds to the descriptions given in the table headings?