Flashcards in Unit 2: Mechanics Deck (146)

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1

## What are scalar quantities?

### They have magnitude (size) but have no direction associated with them.

2

## What are some examples of scalar quantities?

### Temperature, mass, distance, speed, energy and power.

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## What are vector quantities?

### Quantities that have both direction and magnitude.

4

## What are some examples of vector quantities?

### Velocity, force, displacement, acceleration and momentum.

5

## How can two vectors be added together?

### By drawing a scale diagram showing the effect of one vector followed by the other i.e. by drawing them 'nose to tail'.

6

## How can two vectors be added together?

7

## What is the sum of a number of vectors known as?

### The resultant.

8

## What is the parallelogram law?

### When the resultant of two vectors can be found by constructing a parallelogram, the parallelogram is constructed using the two vectors as adjacent sides and the resultant will be the diagonal of the parallelogram.

9

## How can the magnitude of the resultant be found of two vectors at right angles?

### Using Pythagoras' theorem.

10

## How can the magnitude of the resultant be found of two vectors at right angles?

### Using Pythagoras' theorem.

11

## How can you find the angle of the resultant from the horizontal?

### By using the sine and cosine rules.

12

## How do you subtract a vector quantity?

### You can think of it as a adding a negative vector - it is reversed in direction.

13

## How do you subtract a vector quantity?

### You can think of it as a adding a negative vector - it is reversed in direction.

14

## What is the process of resolving vectors into their components?

### A single vector can be replaced by a combination of two or more vectors that would have the same effect.

15

## What is weight?

### The force that acts on a mass due to the gravitational attraction of the Earth.

16

## What is the gravitational field strength (g) on earth?

### 9.81 N/kg

17

## How can you calculate the weight of an object?

### weight (N) = mass (kg) x gravitational field strength (N/kg)

18

## How can you calculate the weight of an object?

### weight (N) = mass (kg) x gravitational field strength (N/kg)

19

## What is the centre of gravity?

### This is when the weight of an object can be treated as a single force acting at a single point in the object.

20

## Where is the centre of gravity of a regular shape with uniform density?

### The geometric centre.

21

## What force is known as the reaction?

### Whenever two solid surfaces touch, they exert a contact force on each other.

22

## What are the two components that a contact force is usually split into?

### The normal contact force acting perpendicularly to the two surfaces and the frictional force acting parallel to the surfaces.

23

## When does a frictional force act between two surfaces?

### Whenever there is relative motion between them, or when an external force is trying to slide them past each other.

24

## When is an object said to be in tension?

### When a force is acting to stretch the object.

25

## What is air resistance?

### The drag an object faces as it moves through the atmosphere as it has to push air out of the way.

26

## What is buoyancy?

### Any objects that are full/partly submerged in a fluid are subject to an upthrust from the surrounding fluid.

27

## What are free body diagrams?

### They are used to show all the external forces acting on an object as they attempt to model the situation so that we can analyse the effects of the forces.

28

## What are free body diagrams?

29

## What does the size of air resistance acting on an object depend on?

### It depends on the area of the object and the density of the air.

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