Flashcards in Forces in Equilibrium Deck (11):

1

## What is the difference between a vector and a scalar?

###
A vector is any physical quantity that has a direction and a magnitude. Where as a scalar is any physical quantity that is not directional.

2

##
What is the principle of moments?

###
An object is in equilibrium when..

the sum of the clockwise moments = the sum of the anticlockwise moments

3

## For a triangle where P is the hypotenuse, and Y is the angle between P and the adjacent (A), how would you calculate the size of the adjacent (A)?

### P cos(y)

4

## For a stationary object the resultant force is...

### Zero

5

##
If two forces are acting perpendicular to each other, how can you find the magnitude of the resultant force?

### Pythagoras' theorem [A^2+B^2=C^2]

6

## How do you calculate the moment of a force?

### Force x Perpendicular distance from the point of action.

7

## What is a moment?

### The turning effect of a force

8

## What are the units for a moment?

### Nm

9

## What is the difference between stable and unstable equilibrium?

###
An object is in stable equilibrium if it can be displaced, and it will return to its original position.

[eg. a ball on a string]

An object is in unstable equilibrium if it can be displaced, but will not return to its original position.

[eg. a plank resting on a round ball]

10

## What is the resultant force for an object moving at a constant velocity?

### Zero

11