Which one of the following quantities has a correct unit? | | Quantity | Unit | | :---- | :---------------- | :-------- | | A | period | m | | B | pulse speed | km·h⁻¹ | | C | frequency | s | | D | potential energy | J·s⁻¹ |
Answer (1)
In this question, we are asked to identify which one among the given options is correctly paired with its unit. Let's go through each option and assess whether the unit matches the corresponding quantity.
Period (m):
The period is the time taken for one complete cycle of oscillation or wave to pass a given point. It is generally measured in seconds (s), not meters (m). Therefore, option A is incorrect.
Pulse speed (km·h⁻¹):
Pulse speed refers to the speed at which a wave pulse travels through a medium. Speed is commonly expressed in units like meters per second (m/s) or kilometers per hour (km/h). The given unit km·h⁻¹ is indeed an appropriate unit for speed. Therefore, option B is correct.
Frequency (s):
Frequency is the number of cycles per second and is measured in hertz (Hz), which is equivalent to inverse seconds (s⁻¹), not just seconds (s). Thus, option C is incorrect.
Potential energy (J·s⁻¹):
Potential energy is the energy stored within an object due to its position, condition, or configuration. It is measured in joules (J), not in joules per second (J·s⁻¹). Joules per second would be a unit of power (watts). Therefore, option D is incorrect.
Based on the analysis, the correct quantity-unit pair is option B: pulse speed (km·h⁻¹) .
