Flashcards in Forces Deck (99)

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1

## What do scalar quantities have?

### Magnitude

2

## What do vector quantities have?

### Magnitude and direction

3

## How are vectors represented?

###
To scale with an arrow:

-specific length representing magnitude

-head representing the direction

4

## Give examples of scalar quantities:

### distance, speed, mass, time, temperature, energy

5

## Give examples of vector quantities:

### displacement, velocity, acceleration, weight, momentum

6

## What do combined vectors give?

### A single resultant

7

## What are the steps to find the resultant vector of two vectors at right angles?

###
1) choose scale for drawing

2) draw the two given vectors carefully, measuring the angle between them

3)complete the rectangle/parallelogram

4) draw the diagonal

5) measure the length and angle of the diagonal

8

## What can a resultant vector be turned into?

### Its vertical and horizontal components

9

## How do planes keep on their desired course despite the wind?

### The pilot has to adjust the velocity vector of the plane to compensate -they would have to determine a velocity relative to the wind speed and direction to ensure travel on the desired course

10

## What is a contact force?

### A force which requires physical contact for interaction (ie. to do work)

11

## What is a non-contact force?

### A force which requires no physical contact for interaction/ to do work

12

## What are examples of contact forces?

### friction, tension, air resistance, normal contact force

13

## What are examples of non-contact forces?

###
-gravitational attraction or weight

-magnetism

-electrostatic force

14

## What is the principle of a gravitational force?

### A massive body will cause another massive body to accelerate ie. a body's speed and/or direction will change when the body is in a gravitational field

15

## What is weight?

### The result of the acceleration due to gravity

16

## How do we calculate weight?

###
weight = mass x acceleration due to gravity

W = mg

17

## What is the unit for weight?

### Newtons

18

## What value has the units N/Kg?

### Gravitational field strength

19

## What value has m/s^2?

### Acceleration due to gravity

20

## What is the relationship between weight and mass?

### they are directly proportional

21

## What type of quantity is mass? what does this mean?

### - an invariant quantity which means it is not dependent on the location of the body

22

## What type of quantity is weight? what does this mean?

### - a variable quantity which means it is dependent on the acceleration due to gravity at the location of the body

23

## What do we use to measure weight?

### a calibrated spring balance (Newtonmeter)

24

## What is the centre of mass/gravity?

### the point associated with a body through which its weight appears to act

25

## Where is the centre of mass for a regular lamina?

### At the geometric centre of it

26

## How would you find the centre of mass for an irregular lamina?

###
- freely suspend the lamina and a plumb line from three different points on the lamina

- the plumb line will hang along a vertical line that contains the lamina's centre of mass

- where the three lines cross, is the location of the lamin'a centre of mass

27

## What is work done?

### the energy transferred by a force changing the displacement of a body

28

## What is the equation for work?

### W = Fs

29

## What is the equivalent of 1J of work?

### 1 Nm

30