The question asks to identify the type of motion that repeats itself. We need to understand the definitions of different types of motion provided in the options.
Correct Option: A) Periodic motion
The question asks for the term that defines the smallest interval of time after which a motion repeats itself. This is a fundamental concept in the study of periodic motion.
B) Period — The period (\(T\)) of a periodic motion is defined as the smallest interval of time after which the motion repeats itself. For instance, if a pendulum swings back and forth, the time it takes to complete one full swing (from one extreme, through the center, to the other extreme, and back to the starting extreme) is its period.
The question asks about the applications of radar technology in various activities. We need to evaluate each given activity to determine if radar can be effectively used for that purpose.
Since radar can be used for all three activities, the correct option is C.
Correct Option: C) All three
The question asks for the SI unit of period. To answer this, we need to recall the definition of period in physics and its fundamental units in the International System of Units (SI).
C) Second — The period is defined as the time taken for one complete cycle or oscillation. The SI unit for time is the second. Hence, the SI unit of period is the second.
The question describes a space-based experiment involving three spacecraft flying in an equilateral triangle formation, with sides one million kilometers long, using lasers between them. This setup is characteristic of missions designed to detect gravitational waves. We need to identify which of the given options matches this description.
D) Evolved LISA is the correct answer. The mission concept for LISA (Laser Interferometer Space Antenna) and its successor, Evolved LISA, involves three spacecraft forming an equilateral triangle with multi-million kilometer arms, using lasers to measure changes in distance caused by gravitational waves. The "one million kilometres" side length is consistent with the scale of such a mission.
The question asks for the unit equivalent of one Hertz. Hertz is the SI unit of frequency. We need to recall the definition of frequency and its relationship with time period to determine its unit.
Correct Option: A) 1 s-1 is the correct unit equivalent for one Hertz, as Hertz is defined as cycles per second.