Units (Forces and Motion)
4 marks · HardThe table below shows several situations or objects. For each, write the SI unit for the quantity shown, using the correct symbol. An example (row 1) is completed for you.
| Situation / Object | Quantity | SI unit (name) | SI unit (symbol) |
|---|---|---|---|
| A car travels 25 metres in 5 seconds. | distance | metre | m |
| A weight-lifter applies a force to raise a barbell. | force | ||
| A moving hockey puck has momentum. | momentum | ||
| A lever turns about a pivot because of a turning force. | moment (of a force) | ||
| An object accelerates at a certain rate. | acceleration |
Complete only the last four rows of the table.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
Must show: force: newton (N), momentum: kilogram metre/second (kg m/s), moment of a force: newton metre (N m), acceleration: metre/second squared (m/s^2)
Also accept: momentum symbol: kg·m/s; moment symbol: Nm (no space considered correct in some texts); acceleration symbol: m/s^2 or m·s^-2
Common mistakes: Confusing newton metre (N m) with newton (N); Mixing up symbol for newton (N) and mass (kg); Writing 'm/s' for acceleration instead of 'm/s^2'; Writing 'm/s^2' for velocity
Show mark scheme and worked solution
Marking points
B1 · 1 mark · Correct unit and symbol for force: newton (N)
B2 · 1 mark · Correct unit and symbol for momentum: kilogram metre/second (kg m/s)
B3 · 1 mark · Correct unit and symbol for moment of a force: newton metre (N m)
B4 · 1 mark · Correct unit and symbol for acceleration: metre/second squared (m/s^2)
Worked solution
To answer, fill in the SI name and symbol for each physical quantity:
| Situation / Object | Quantity | SI unit (name) | SI unit (symbol) |
|---|---|---|---|
| A car travels 25 metres in 5 seconds. | distance | metre | m |
| A weight-lifter applies a force to raise a barbell. | force | newton | N |
| A moving hockey puck has momentum. | momentum | kilogram metre/second | kg m/s |
| A lever turns about a pivot because of a turning force. | moment (of a force) | newton metre | N m |
| An object accelerates at a certain rate. | acceleration | metre/second squared | m/s^2 |