P3.2 Centre of mass and moments

Question 1

What is a moment and what is a moment measured in?

Answer 1

The turning effect of a force

Nm

Question 2

Describe the moments of an object that is not turning

Answer 2

• Total CLOCK moment must be exactly BALANCED
• by the total ANTI moment
• about any PIVOT

Question 3

Give three examples of simple levers

Answer 3

Scissors
Wheelbarrow
Pliers

Question 4

When will there be a resultant moment and what will this cause?

Answer 4

-If the LINE OF ACTION of the WEIGHT of an object
lies OUTSIDE THE BASE of the object
-The body will topple

Question 5

What is the centre of mass of an object?

Answer 5

The point where the mass of the object is thought to be (concentrated)

Question 6

How do you find the centre of mass of a suspended object?

Answer 6

• SUSPEND shape
• attach PLUMB line (to point of suspension)
• DRAW LINE on card where string rests
• SUSPEND; another point
• DRAW second LINE where string rests
• cross = centre of mass

Question 7

What is a plumb line?

Answer 7

A piece of string with a weight hanging from it

Question 8

What affects the time period of a pendulum?

Answer 8

The length of the pendulum

Question 9

Give 3 examples of pendulums

Answer 9

Playground swings
Pirate ship rides
Inside some clocks (e.g. grandfather clocks)