Forces in Equilibrium Flashcards Preview

AS Level Physics > Forces in Equilibrium > Flashcards

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

How can you get an object to 'topple' ?

Move the line of action of weight (a line vertically down from the centre of mass) outside of its base area.