PHYSICAL SCIENCE FINAL

Who is the Greek philosopher who was able to explain what causes the phases of the moon and according to him, the moon shone only by reflected sunlight?

Aristotle is the father of Natural Science. He believed that the Earth is not flat. One of his observations is the disappearing ship where he could see the tops of their sails before he saw the rest of the ship. Which of the following is the statement supports the idea that the Earth is not flat?

Natural optical phenomena, such as mirages, haloes, sun dogs, and rainbows are brought about by how light behaves as it interacts with matter.

Which is not responsible for the formation of a rainbow?

Who developed the theory of special relativity?

What is the speed of light?

Imagine a scientist conducting experiments aboard a spacecraft moving at a constant velocity in deep space. The scientist measures the speed of light emitted from a stationary source on the spacecraft and finds it to be exactly 300,000 km/s. Simultaneously, another scientist on Earth measures the speed of light emitted from the same spacecraft and also finds it to be 300,000 km/s, despite the spacecraft's motion relative to Earth. This observation supports one of the fundamental principles of Einstein's special theory of relativity. Which of the following statements aligns with this principle?

Imagine you are an astronomer tasked with determining the distance to a star relatively close to Earth, located less than 100 light-years away. You know that the star’s position seems to shift slightly when viewed from different points in Earth’s orbit around the Sun. This apparent shift, relative to the background of more distant stars, can be measured to calculate its distance.

There are four possible methods:

Method 1: Radar – This modern method of measuring distances in our solar system and nearby heavenly bodies.

Method 2: Cepheid Variables –This method can be used as measurements of distance of a few tens of millions of light-years.

Method 3: Parallax – This method relies on no assumptions other than the geometry of the Earth’s orbit around the sun.

Method 4: Redshift – This method can be used for very far objects beyond 1 billion light-years.

Based on this observation, which method would you use to accurately measure the star's distance?

George Lemaitre observed that the galaxies are moving away from each other and proposed that the universe must have been much smaller in the past. What is his theory that describes how the universe expanded rapidly from a small point into the vast cosmos we know today?

Babylonian and Egyptian civilizations used a primitive version of a sundial, called gnomon shown in the picture, in systematically observing the motion of the sun. By looking at the shadows that the gnomon casts, they were able to observe that the sun rises in the eastern part of the sky and sets in the western part of the sky.

Which of the following time will the shadow reaches its highest point?

Green cellophane will only allow green light to pass through it; a red one will only allow red light to pass. The cellophane absorbs other colors of light. That is why a red light can easily pass through a red cellophane compared to a green cellophane. As a general rule each color filter (e.g. glass or cellophane) will only allow light of its own color to pass through.

Which of the following observations does not correctly explain the passing of light through a cellophane?

Mirage is caused by the total internal reflection of light at layers of air at different densities. The picture shows the formation of mirage. Which of the following is responsible for the formation of mirage?

Imagine you're an observer on Earth, looking up at a spacecraft traveling through space. The spacecraft is moving at a speed of 80% of the speed of light relative to you. This high speed triggers an interesting phenomenon known as length contraction, which is a key concept in Einstein’s theory of special relativity.

This phenomenon happens because, according to special relativity, as an object moves faster, the space along the direction of motion appears contracted to an external observer. The faster the object moves, the greater the effect of contraction becomes. At 80% of the speed of light, this effect is noticeable but not as extreme as at speeds closer to the speed of light (such as 99%).

How would the length of the spacecraft appear to the observer’s point of view?

You are learning about the expansion of the universe and how scientists observe galaxies moving away from Earth. Your instructor introduces Hubble’s Law, which states that galaxies recede from us at speeds proportional to their distances. This means that the farther away a galaxy is, the faster it appears to be moving away from us. Scientists use this relationship to determine distances to far-off galaxies by measuring their speed and applying Hubble’s Law. By observing the speed at which a galaxy is receding, we can infer its approximate distance from Earth.

Using Hubble’s Law, what can be observed if a galaxy is moving away from us at a very high speed?

An astronaut aboard a spacecraft is traveling at 90% the speed of light relative to Earth. The astronaut looks out of the spacecraft window and observes a clock on Earth through a powerful telescope. The astronaut notices that the clock on Earth appears to tick more slowly compared to the clock inside the spacecraft. To the astronaut, seconds on the Earth clock take longer to pass. Meanwhile, an observer on Earth looks up at the spacecraft through their telescope and observes the clock aboard the spacecraft. The observer on Earth notices the opposite effect: the clock aboard the spacecraft appears to tick more slowly than the one on Earth.

This phenomenon, where each observer perceives the other's clock as running more slowly due to their relative motion, which principle of relativity is being applied?

According to Special Theory of Relativity, the speed of light is the same in all inertial frames of reference and is independent of the motion of the source.

A person on another planet shines a flashlight at you. The planet and the earth are both in the same reference frame and are not moving relative to each other. At the same instant that the person shined the flashlight at you, a person on a spaceship passing that planet and moving toward you at 0.5 c also shined a flashlight at you.

Which light pulse will reach you first the light from the other planet or the light from the spaceship, and why?