Flashcards in CE 10224A - Science for CE (Physics) Deck (17)

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1

## What are the 2 branches of dynamics?

###
- Kinematics (the study of the motion of point masses or rigid bodies. Focuses on calculating position, displacement, velocity and acceleration (not the forces causing them)

- Kinetics (the study of the forces that produce or change motion)

2

## What are the types of friction?

###
Static frictional force, Fs - the force, opposing direction of motion and resulting in a static condition.

Kinetic friction, Fk - frictional force opposing motion as the object is moving.

3

## How is static friction calculated?

###
πΉπ = πsπΉΞ

Where:

Fs is static friction

πs is coefficient of static friction

FN is the normal force

4

## How is kinetic friction calculated?

###
πΉπ = πkπΉN

Where:

Fk is kinetic friction

πk is coefficient of kinetic friction

FN is the normal force

5

## In terms of friction coefficient, what causes an object to remain stationary?

### When kinetic frictional force is less than force of static friction.

6

## How is drag force calculated?

###
π· = 1/2πΆππ΄π£^2

Where:

D is drag force

C is the drag coefficient

π is fluid density

A is cross-sectional surface area perpendicular to v

v is fluid velocity

7

## How is centripetal force calculated?

### ππ = πππ / π

8

## How is velocity and angular velocity calculated?

###
π£ = 2ππ / π

π£ = 2πππ

π£ = ππ

π = 2π / π

9

## How is centripetal acceleration calculated?

###
ππ = π^ππ

ππ =π^π / π

10

## How are forces analysed in non-uniform circular motion?

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If πΉπ‘ππ‘ is acting at an angle, then this force causes a non-uniform circular motion

Analysis into x, y-axis components:

- There's a force directed towards the centre of the circle causing the centripetal acceleration, ππ

- A tangential force causes a tangential acceleration called ππππ.

These accelerations are perpendicular to one another.

11

## For non - uniform circular motion, how is total acceleration and angular acceleration calculated?

###
ππ = π^ππ

ππππ = π
π/π
π = π π
π/π
π

ππππ = (ππ^2 π+ππππ^2)^1/2

ππππ= π
π/π
π

= (ππβππ) / (ππβππ)

12

##
How are angular and tangential accelerations related?

### ππππ = π*π πππ

13

## What's centrifugal force?

### Ff, a ββ reactiveββ force acting upon a body due to rotation, and on the opposite direction of the centripetal force, at an equal magnitude, away from the centre of rotation.

14

## What's ββapparentββ centrifugal force?

###
Fapp, a force which pushes the object away from the centre of rotation.

This is not part of any interaction, but it is the objects inertia.

15

## How is work done calculated?

###
π = πΉπππ π(π₯π΅ β π₯π΄)

π = π(π2 β π1)

16

## How is gravitational potential energy calculated?

###
[E = mgh]

U = mg(h2-h1)

17