Question

which of the following are the correct units for speed? choose all that apply. cm ft/min kn h in s mi/s m m/s² yd cm/y in/min²

Explanation:

Speed is defined as the distance traveled per unit of time. So, its units should be in the form of distance unit over time unit.

• \(cm\) (centimeter) is a unit of length (distance), not speed.
• \(ft/min\) (feet per minute) is distance (feet) over time (minute), so it is a unit of speed.
• \(kn\) (knot, \(1\) knot \( = 1\) nautical - mile per hour) is a unit of speed.
• \(h\) (hour) is a unit of time, not speed.
• \(in\) (inch) is a unit of length (distance), not speed.
• \(s\) (second) is a unit of time, not speed.
• \(mi/s\) (miles per second) is distance (miles) over time (seconds), so it is a unit of speed.
• \(m\) (meter) is a unit of length (distance), not speed.
• \(m/s^{2}\) is a unit of acceleration (since acceleration \(a=\frac{\Delta v}{\Delta t}\), and \(v\) has units of \(m/s\), so \(a\) has units of \(\frac{m/s}{s}=m/s^{2}\)), not speed.
• \(yd\) (yard) is a unit of length (distance), not speed.
• \(cm/y\) (centimeters per year) is distance (centimeters) over time (years), so it is a unit of speed.
• \(in/min^{2}\) is a unit of acceleration (because it is a unit of length over time - squared), not speed.

Answer:

ft/min, kn, mi/s, cm/y