IB物理真题精讲 用真题来查漏补缺助阵你的5月大考

马上就是5月的IB大考了，很多同学应该都在准备复习计划了，下面给大家带来一些不同知识点的IB物理真题，同学们都赶紧来看看这些题你都会做吗？

ideal gas

The pressure of a fixed mass of an ideal gas in a container is decreased at constant temperature. For the molecules of the gas there will be a decrease in

A.  the mean square speed.

B. the number striking the container walls every second.

C. the force between them.

D. their diameter.

解析

此题考察的是ideal gas理想气体中pressure的影响因素。这里的gas pressure需要使用kinetic theory来解释，由于gas molecules与wall of the container之间的collisions, each molecule produces a force on the wall, forces average out to produce a uniform pressure. 由此可以看出collisions相关的因素是能影响到pressure。选项C与D虽然与ideal gas有关，但更多是关于ideal gas的assumptions，与题目关联有限。选项A较容易被选择因为mean square speed显然与kinetic energy有关，很容易误以为是正确选项；但题目中有很关键的constant temperature, For ideal gases,  图片mean square speed is proportional to the temperature, constant temperature so constant mean square speed. 而选项B，由于mean square speed没变，gas molecule的kinetic energy不变，而collisions的频率减少，则产生的pressure会降低，故选项B为正解。

Electric Field Strength

Q: The radius of a charged spherical conductor is R. Which of the following graphs best shows how the magnitude of the electric field strength E varies with distance r from the centre of the sphere?

解析

但是这里要特别注意的是对于这类conducting sphere，它的内部经过测试是没有electric field存在，因此field strength为0。此外，考虑electric field strength在sphere表面时，这些field vectors经过加减，导致最终的electric field 方向是与surface perpendicular。考虑到内部electric field strength为0，在外部则与r2成反比，故选项D是正解。

One-Dimensional Motion Problems

A driver has a reaction time of 0.50 s, and the maximum deceleration of her car is 6.0 m/s2. She is driving at 20 m/s when suddenly she sees an obstacle in the road 50 m in front of her. Can she stop the car in time to avoid a collision?

解析

关键在于需要理解反应时间的意义。反应时间内驾驶员不做回应，该时间内汽车仍然维持初始的运动速度！因此：需要注意这里是减速，加速度符号为负。滑行距离小于50米，可以避免碰撞。

Capacitor

A capacitor of capacitance C discharges through a resistor of resistance R. The graph shows the variation with time t of the voltage V across the capacitor.

The capacitor is changed to one of value 2C and the resistor is changed to one of value 2R. Which graph shows the variation with t of V when the new combination is discharged?

解析

此题考察的是discharge circuit中potential difference, V和time, t的关系。实际上，Q, V, I都与t有着十分类似的关系，可以一起记下来。

where time constant, τ=RC

而本题中，R与C都增加了两倍，independent variable与原先相比减小到1/4，由数学中Transformation的知识可以得出，graph experiences horizontal stretch by a factor of 4，故选项B为正解。

De Broglie Wavelength

A beam of electrons is accelerated from rest through a potential difference V. The de Broglie wavelength of the electrons is λ. For electrons accelerated through a potential difference of 2V the de Broglie wavelength is

解析

以上就是几道IB物理的真题了，同学们在复习IB物理时可以结合真题来，根据真题来查漏补缺。IB物理一直被众多同学默认为是最难的IB科目之一，所以想要考高分的同学必须要努力呀！无论你是IA/EE还是其他IB科目有问题，您都可以前来橡沐哦，橡沐常年开设IB辅导课程。赶紧点击【预约试听】了解更多课程详情吧！

更多课程详情

IB物理如何考到7分 这5个高效IB物理学习方法大神们都在用

IB物理和SAT物理哪个更简单想申请美本的你会怎么选