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Flashcards in 3.2 Forces In Action Deck (41)
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1

Newton's second law.

F= ma

2

What are the four fundamental forces of nature?

-gravitational force
-electromagnetic force
-weak interaction
-strong interaction

3

Which is the weakest of the four fundamental forces?

Gravitational

4

What does the electromagnetic force do?

Holds atoms and molecules together.

5

How can the electromagnetic force be described?

The exchange of photons between charged particles of magnetic materials.

6

What is the weak interaction responsible for?

Radioactive decay.

7

What is the range of the weak interaction?

10-18m

8

What is the strong interaction responsible for?

Holding subatomic particles together.

9

What is the strongest fundamental force of nature?

The strong interaction.

10

What is the range of the strong interaction?

10-15m

11

What are the five main types of force we need to know about?

Tension, normal contact force, upthrust, friction and drag.

12

What is the equation for tension?

Tension = mass x acceleration.

13

What is upthrust?

The upwards force that a liquid or gas exerts on a body floating in it due to the water displaced.

14

When will an object move at terminal velocity?

When the magnitude of the body's weight becomes equal to the sum of the drag and the upthrust and the resultant force is 0.

15

What is a fluid?

A liquid or a gas.

16

What is p in the equation for drag?

The density of the fluid.

17

What is A in the equation for drag?

The cross sectional area of the moving object

18

What is v in the equation for drag?

Velocity of moving object.

19

What is equilibrium?

When all the Coplanar forces are balanced.

20

How can we work out the resultant of two forces acting on a body?

-a scale drawing
-right angled vector triangle.

21

What does a triangle of forces represent?

The direction and magnitude of three coplanar forces that are acting on an object in equilibrium.

22

Equation for turning moment?

Magnitude of force (N) x perpendicular distance from a fixed point (m)

23

Unit of turning moment?

N m

24

Define moment of force or turning moment.

The product of the and perpendicular distance of its kind of action from the point or axis.

25

What is the fancy name of the pivot?

Fulcrum

26

Define the principle of moments.

For an object to in rotational equilibrium, the sum of the clockwise moments about a point must be the sum of the anti-clockwise moment about the same point.

27

What are the two conditions for equilibrium?

1) resultant force on the objects must be 0
2) sum of clockwise = sum of anti-clockwise

28

What is drag?

Friction force experienced by an object travelling through a fluid.

29

What is Archimedes principle?

A law stating that a body totally or partially immersed in a fluid is subject to an upward force equal in magnitude to the weight of fluid it displaces.

30

When does a couple occur?

When two equal, antiparallel forces act to produce rotation - no linear motion occurs.