IB物理考試包括3個(gè)paper，paper1是選擇題，paper2和paper3是簡(jiǎn)答題，對(duì)于很多學(xué)生來(lái)講paper3是非常有難度的，為了幫助大家更好的應(yīng)對(duì)這部分，今天留求藝留學(xué)為大家分享IB物理HL Paper3真題示例及備考技巧希望對(duì)大家有幫助。

IB物理HL Paper3真題示例

1.) A wheel of a mass of 0.27 kg that consists of a cylinder is mounted on the central shaft. The radius of the shaft is 1.4 cm and the cylinder, 4.2 cm. The shaft sits on two rails and is allowed to rotate and spin freely.

a.) The wheel is released from a stationary position and it rolls down the rail without slipping from Point A to Point B. The picture below shows the setup

The wheel leaves the rails at Point B and travels along a flat track from Point B to Point C. For a short while, a frictional force F exists towards point C between the edge of the wheel and the flat track

i.) The moment of Inertia of the wheel is 1.5 x 10-4?kgm2. Define inertia
Answer
Inertia is a property of matter that causes it to resist changes in velocity. It remains at the state of rest or in uniform motion in the same straight line unless acted upon by some external force.

ii.) While the wheel moves from Point A to B, the center of mass falls through a vertical distance of 0.43 m. Determine the translational speed of the wheel from Point A to Point after its displacement.
Answer
Kinetic Energy + Rotational KE = Gravitational Potential Energy
Therefore, ? mv2?+ ? I x v2/r2?= mgh where r is the radius of the shaft
? x 0.27 x v2?+ ? x 1.5 x 10-4?x v2/ (1.96 x 10-4) = 0.27 x 9.81 x 0.43
Rearranging and finding v, we have v = 1.48 m/s

iii.) Determine the angular velocity of the wheel at Point B
Answer
Angular velocity = velocity / radius (in meters)
Therefore, Angular velocity = 1.48 / 0.014 = 105.7 → 106 rad/s

iv.) Describe the effect of the frictional force on the linear speed of the wheel
Answer
Since the force is in the direction of the motion, the linear speed of the wheel increases.

v.) Describe the effect of the frictional force on the angular speed of the wheel
Answer
The angular speed decreases since the force gives rise to an opposing torque on the wheel.

2.) In an experiment, a student rolls paper into cylinders with the same diameter but different heights. The student then placed a fixed load on top of each of the cylinders one by one beginning with the cylinder with the shortest height. After, they recorded the height H of the first cylinder that was about to collapse. They then repeated the same process with different diameters of the cylinder. The graph below shows all the data recorded by the student. It is predicted that H (height) = cD2/3?where c is the constant

a.) Explain why the students data supports the theoretical prediction
Answer
According to the theoretical prediction, H3?is proportional to D2. When drawn in the graph, it is a straight line that goes through the origin – which is seen in the students graph above. Hence, it suggests that the data matches the prediction.

b.) Determine the constant c with an appropriate unit
Answer
c = gradient of the line
c = (46 – 12) / (16 – 4) = 34/12 = 2.83
c3?= 2.83 → c = 1.41
The unit for c is m1/3

c.) State one factor that would determine the constant c
Answer
The constant c could vary due to a number of factors. Some of them include the thickness of the paper, the weight of the fixed load and the number of times the paper is rolled into a cylinder (thickness of the cylinder itself).

IB物理HL Paper3備考技巧

1、paper3里的需要解釋一個(gè)現(xiàn)象為什么會(huì)這樣的問(wèn)題，通常會(huì)考得最靈活。要是同學(xué)們遇到完全不知道如何下筆的這類題，可以先盡力找到相關(guān)的知識(shí)點(diǎn)或/和公式，把這個(gè)知識(shí)點(diǎn)先解釋一遍，然后根據(jù)題意，把這個(gè)知識(shí)點(diǎn)帶進(jìn)入題的情況 里說(shuō)一遍，為什么這個(gè)情況下會(huì)出現(xiàn)這個(gè)知識(shí)點(diǎn)描述的情況，就可以啦。

2、P3同樣也是要多多刷題，Option的部分就不會(huì)有問(wèn)題了。P3的Section A的Measurement and Uncertainties反而難度會(huì)比較大，因?yàn)榭嫉煤莒`活。需要同學(xué)們熟練掌握如何 計(jì)算uncertainties，以及對(duì)題目里描述的實(shí)驗(yàn)的徹底理解，剩下的就是根據(jù)題意找出適用的相關(guān)知識(shí)點(diǎn)和公式了。

【微語(yǔ)】留學(xué)是一條漫長(zhǎng)的路，不要因小失大。在留學(xué)中，你可以感悟人生，體驗(yàn)文化，磨礪意志，陶冶情操，但千萬(wàn)不要迷失方向。