Latihan Soal STS IPA Kelas 8 Semester 2 Kurikulum Merdeka Dengan Pembahasan Lengkap

Summary

This educational video is designed to help grade 8 students prepare for their midterm science exam. It covers a range of topics, including pendulum motion, frequency, wave characteristics, sound, light, the structure of the human eye, and atomic composition. The video offers practice questions on these subjects, helping students understand concepts such as frequency, wave speed, and the functioning of different parts of the eye. The instructor explains each question step-by-step, reinforcing key scientific principles and encouraging students to review the material for a better understanding.

Takeaways

• 😀 The pendulum starts at rest at position A and swings between points A, B, and C. The motion follows a pattern, and the number of vibrations is two.
• 😀 Frequency of an object can be calculated using the formula F = n/t. For an object that vibrates 50 times in 2 seconds, the frequency is 25 Hz.
• 😀 The correct number of waves in a given graph is 2.5 waves, as the graph passes through two troughs and three crests.
• 😀 The speed of a wave can be calculated using the formula V = λ/T. With a wavelength of 2 meters and a period of 0.5 seconds, the speed of the wave is 4 m/s.
• 😀 To hear sound, three conditions must be met: a sound source, a medium to transmit the sound, and a receiver to detect the sound. The frequency is not required for hearing.
• 😀 Different sound waves have varying frequencies, amplitudes, and sound colors. These factors determine the loudness and quality of sound.
• 😀 Humans can hear sounds within the frequency range of 20 Hz to 20,000 Hz, known as the audible frequency range.
• 😀 Diffuse reflection occurs when light hits an uneven surface, causing the reflected light to scatter in multiple directions.
• 😀 Refraction of light happens when it passes through two media with different optical densities, causing the light to bend.
• 😀 The outer layer of the human eye, called the sclera, forms the cornea, and it plays a vital role in focusing light.
• 😀 The iris of the eye controls the amount of light entering the eye by adjusting the size of the pupil. The lens is responsible for focusing the light onto the retina.
• 😀 The eye contains two types of photoreceptor cells: rods (for low light) and cones (for color vision).
• 😀 Metals have distinct properties like electrical conductivity, malleability, and luster, while non-metals exhibit different characteristics.
• 😀 The naming of chemical elements is regulated by the International Union of Pure and Applied Chemistry (IUPAC).
• 😀 Atoms consist of protons, neutrons, and electrons. These subatomic particles are the fundamental components of matter.
• 😀 The valence electrons, which determine an element's chemical behavior, are found in the outermost shell of the atom.
• 😀 The centrifugation method is used to separate mixtures based on the movement of particles using centrifugal force.

Q & A

What is the number of vibrations produced by the pendulum when it moves from position A to position B and back to A?

The pendulum produces 2 vibrations as it moves from A to B to C and back to A, completing one full oscillation each time it returns to position A.

How do you calculate the frequency of a vibrating object that completes 50 vibrations in 2 seconds?

The frequency can be calculated using the formula F = n / t, where n is the number of vibrations (50) and t is the time in seconds (2). The frequency is 50 / 2 = 25 Hz.

What is the correct interpretation of the wave pattern described in the transcript?

The wave pattern is interpreted as 2.5 waves, since it includes two valleys and three peaks, which together represent half and one full wave.

How do you calculate the speed of a wave if the wavelength is 2 meters and the time period for one wave is 0.5 seconds?

The wave speed can be calculated using the formula V = λ / T, where λ is the wavelength (2 m) and T is the time period (0.5 s). The speed is 2 / 0.5 = 4 m/s.

What are the necessary conditions for sound to be heard?

For sound to be heard, there must be a source of sound, a medium through which the sound travels, and a receiver (such as the human ear). There is no need for Hertz in this case.

Why does the strength of sound vary, even if it travels through the same medium?

The strength of the sound varies because sound waves have different frequencies, amplitudes, and tonal qualities, which affect their perceived loudness and pitch.

What is the frequency range that humans can hear?

Humans can hear sound frequencies between 20 Hz and 20,000 Hz (also known as the audible range).

What causes diffuse reflection of light?

Diffuse reflection occurs when light strikes an uneven surface, causing the light to scatter in many directions rather than reflecting off in a single direction.

What causes the refraction of light?

Refraction occurs when light passes through two different media that have different optical densities, causing the light to change speed and direction.

What is the shape of the lens in the human eye?

The lens of the human eye is biconvex, meaning it is curved outward on both sides to focus light onto the retina.