What makes up a reference frame in mechanics?

Question

Which components belong to a reference frame? Select the correct answers.

Answer choices

1. A reference point.
2. A device for measuring time.
3. A reference body.
4. A device for measuring length.
5. A coordinate system.

Answer

A reference body, a coordinate system, and a clock — options 2, 3, and 5.

Explanation

To describe motion, specify the body relative to which motion is considered, the object's position, and the time at which that position is given.

A reference frame therefore includes:

• a reference body, relative to which motion is described;
• a coordinate system attached to it, to specify position;
• a time-measuring device (clock), to associate positions with times.

A separate length-measuring instrument or reference point does not replace this combination. Choose 2, 3, and 5.