Flashcards in Mechanics Deck (49)

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1

## What property does a scalar quantity have?

### Magnitude only.

2

## What properties do vectors have?

### Both magnitude and direction.

3

## Examples of vector quantities:

### Velocity, displacement, acceleration, forces, momentum, weight, moments.

4

## Examples of scalar quantities:

### Speed, distance, electrical power, charge, mass, energy, current, potential difference.

5

## Speed is...

### ...rate of change of distance.

6

## Velocity is...

### ...rate of change of displacement.

7

## Acceleration is...

### ...rate of change of velocity.

8

## Equation for acceleration using velocities:

### a=Δv/Δt

9

## What is unit acceleration measured in?

### ms^-2

10

## The gradient of a velocity time graph represents what?

### Acceleration.

11

## The area under a velocity time graph represents what?

### Displacement.

12

## Define a moment.

### The turning effect of a force at a distance perpendicular to the force.

13

## Equation for moments:

###
M = Fd

Where:

M is the moment.

F is the force.

d is the distance perpendicular to the force from the pivot.

14

## Moments are measured in what?

### Nm.

15

## Centre of mass is what?

### The mean position of the mass of an object.

16

## Centre of gravity is what?

### The position at which weight acts if the object is considered as a single position; the point at which there is no moment due to weight.

17

## In a uniform gravitational field, what can be said about the centre of mass and the centre of gravity?

### They are in exactly the same place.

18

## An object is stable, when?

### If the line of action from the centre of gravity lies within the base of the object.

19

## How can an object be made more stable?

### An object can be made more stable by lowering the centre of gravity or by widening the base.

20

## What is the principle of moments?

### A system can be said to be in equilibrium if the sum of the total anticlockwise moments equals the sum of the total clockwise moments.

21

## What equipment can be used to find the centre of gravity of an object?

###
A clampstand.

A plumbline.

A nail.

22

## Equation for kinetic energy:

### Ek = 1/2 mv^2

23

## Equation for gravitational potential energy:

### ΔEp = mgΔh

24

## Elastic potential energy equations:

###
Eel = 1/2 Fx

or

Eel = 1/2 kx^2

25

## Equation for work done:

### W = Fscosϴ

26

## What can a vector be resolved into?

### A horizontal component and a vertical component.

27

## How do we resolve to find horizontal and vertical components of vectors?

###
Use trigonometry.

Sine to find the vertical component.

Cosine to find the horizontal component.

28

##
What does SUVAT stand for?

###
S for displacement/m.

U for initial velocity/ms^-1

V for final velocity/ms^-1

A for acceleration/ms^-2

T for time/s

29

## What are the four equations of motion?

###
v=u+at

s=ut+1/2at^2

v^2=u^2+2as

s=1/2(u+v)t

30