# Mechanics and waves Flashcards

What is the centre of gravity

A point on the object where gravity appears to act generally in the middle but not always

Why is a tall glass easily toppled

It is easily toppled when the line of action of its weight is beyond the edge of the base then the glass tips right over

Definition of moment

The product of the force * the perpendicular distance from the pivot

What is the eqaution for moments

Moments = FD

What is the pivot point

The point of Whitchurch an object rotates about

How do you know when an object is equilibrium

When the sum of clockwise moments equals the sum of anti-clockwise moments and there is no resultant force

How would you calculate the centre of mass of a piece of card

Hang up the card and suspend a plumb line from the same place

Mark the position of the thread

Repeat the above steps with the card suspended from different places

Where these lines intersect is the centre of mass

Definition of equilibrium

No resultant force

No resultant moment

What is the eqaution for momentum

P = mass * velocity

How do you work out velocity.

Total distance / total time

How do you work out GPE

GPE = MGH

How do you work out Ke

1/2 Mvsqaured

What is a scalar measurement

An amount just with a magnitude

Energy work done

Distance around a circle

What is vector measurement

An amount with a direction

Distance you are form the start of circle

What is an example of a scalar measurement

Speed

What are examples of vector measurements

Displacement

Force

velocity

Acceleration

What is the change in momentum also called

An impulse

How can you calculate F

F= impulse/time