Archive for the ‘algebra’ Category

h1

QWERTY Math for MAC

April 16, 2018

QWERTY Math uses KEYBOARD SHORTCUTS

There are 10 math questions

(pdf version and pdf ans below).

The boxed sections are keyboard math symbol shortcuts.

When the students push these keys the Qs finally make sense.

eg. option v = square root sign

BUT:

1. They must have a computer with a KEYBOARD (not a tablet)

2. The computer must be a MAC*

*Mathspig tried to find the QWERTY Math shortcuts on her old PC and it went crazy!!!! 

QWerty Math for MAC pdf

Qwerty Math for MAC ANS

Advertisements
h1

WINTER OLYMPICS: How ski Jumpers Use Math to Increase their Jump Length

February 16, 2018

While air resistance has little impact on aerial skiers it is a significant factor used by ski jumpers to increase their jump distance.

The significant maths for ski jumpers is therefore X-section area.

Here is the jump at Pyeong Chang, 2018. Just imagine going down that at top speed!!!

              A ski jumper is set to jump in Pyeongchang.

                   Casey Larson USA Pyeong chang 2018

Ski jumpers increase their speed going down the ramp by reducing their X-section area:

Lindsey Van, USA, practicing in a wind tunnel

           Lindsey Van, USA, practicing in a wind tunnel

Once they leave the ramp, ski jumpers try to increase their X-section area like Ski Divers to slow their vertical fall. But they have to land safely so they keep their skis at a minimum  angle.

Abby Hughes, USA, practicing in a wind tunnel.

Abby Hughes, USA, practicing in a wind tunnel.

Abby Hughes, USA, in the air

          Abby Hughes, USA, in the air

Here are the X-section areas for Abby Hughes*:

Abby Hughes X-section

Here is the formula for Air Resistance of Drag:

D = ½CApv2

Where C is the drag coefficient or constant, which depends on the shape and spin of an object. It is found by testing the object in a wind tunnel.

A is the X-section Area,

p is the density of the air and

v the velocity of the object.

More here.

As Abby Hughes has tripled here X-section area in the air she will have tripled the vertical drag during her jump. This will slow here decent.

*Mathspig calculated the X-section area by the old fashioned method of counting squares and rounding off the final count. Mathspig sized the two pics of Abby Huges so that her head was the same size in both pictures.

h1

Winter Olympics: Why do figure skaters spin so fast?

February 15, 2018

Here is the sensational pairs team from the 2018 Winter Olympics.

But why do ice skaters spin so fast?

Here is the math!

REASON  1:

Well, mathspiggies, the girl in this video is right. Angular momentum remains constant unless external forces are applied.

L = mvr

L = angular momentum

v = linear velocity

r = separation of object

Louisa Barama, USA

Louisa Barama, USA

Let’s have a look at this equation:

Figure skate maths1

The fastest spin on ice skates was achieved by Natalia Kanounnikova (Russia) with a maximum rotational velocity of 308 RPM (rotations per minute) at Rockefeller Centre Ice Rink, New York, USA on 27 March 2006. See Guinness Book of Records.

 Record spin :  vr = 308 RPM

Other spins include:

Mao Asada, Japan, triple Axel

Mao Asada, Japan, triple Axel

Triple Axel spin vr = 220 – 280 RPM

……………………………………………………………………………………………..

 Maximum Triple Axel spin vr = 402 RPM

Skaters can spin faster during a triple axel jump because there is no friction from the ice slowing their spin.

To complete a quad axel, it’s estimated that the skater would have to rotate in the air at:

540 rpm.

…………………………………………………………………………………

Camel spin vr = 90 RPM

More info here.

Kim Yuna, South Korea

Kim Yuna, South Korea

…………………………………………….

REASON 2:

How can a figure skater move from

a camel spin into a very fast standing spin?

Now, mathspiggies, you must separate Linear Velocity (v1 ) from Angular Velocity (vr ). Linear Velocity is measured in m/sec ie. it is the speed of, say, a skaters foot around the circle. Angular Velocity is measured in either RPM (Revolutions Per Minute) or degrees or Radians per minute. Ie. It is the rate of spin. We can’t judge how many m/sec a skaters foot is moving in a circle. We can only see how fast they spin. In other words, we see their Angular Velocity. When a skaters foot is in the Camel position that foot travels in a very big circle.

But when that same foot is in a Triple Axel postion it moves in a very, very small circle.

Patrick Chan, Canada, Camel Spin

Patrick Chan, Canada, Camel Spin

Patrick Chan, Canada, Triple Axel

Patrick Chan, Canada, Triple Axel

figure skate maths 2

By halving the radius, firstly, a skater’s Linear Velocity doubles due to the conservation of angular momentum.

Then, secondly, by halving the radius the circumference of the circle moved by , say, the skaters foot is halved.

Overall, by doubling the velocity around the circle and halving the circumference a skater increases their rotational velocity by a factor of 4.

Look at the numbers:

Camel spin vr = 90 RPM

…………………………………………………………………………………

Triple Axel spin vr = 4 x 90 RPM = 360 RPM

That’s about right.

h1

WINTER OLYMPICS: One Rule Aerial Skiers Cannot Break

February 10, 2018

Aerial skiers aim for height rather than length. Their aerial flight times are much smaller than ski jumpers so air resistance has minimal impact.

In fact, there is one law the aerial skiers cannot break. It is the law of gravity.

Here is an equation for  projectile motion from Wired magazine.

Screen grab from Wired Magazine

Screen grab from Wired Magazine

The equation for projectile motion also applies to Motorbike Jumps and Longbow Arrows.

Here is the x-y graph for different launch angles.

trajectory wired magazine

trajectory wired magazine

 

You can go to this page for complete calculations. Aerial skiers twist and turn but their CENTRE OF GRAVITY must follow this graph. More on centre of Gravity at The Great Back Pack Attack ie.

The centre of gravity of Aerial Skiers must follow a

parabolic curve.

Aerial Parabola final 2

Rocky Maloney Winter X Games Aspen

Rocky Maloney Winter X Games Aspen

h1

Hello 2018 This is why you need maths!

December 30, 2017

Hello Little Munchins,

,…………………………………………..…………………………….

Maths can save your life. How? Read on.

,…………………………………………..…………………………….

Sadly, a car has been used as a weapon again in my city, Melbourne. 

,…………………………………………..…………………………….

When talking to science types about the Maths of a Car Used as a Weapon they say ‘Yeah! Right! As if you are going to stand around doing the maths when a car is heading towards you!!!!.’……………………

NO!…………………………………………..……..

You don’t do the maths in a crisis. You do it before hand. And it will change your view of car safety for all time.

METRIC:

Maths of a Car Used as a Weapon 

If you are 9 m away from a car travelling at 60 kph, you DO NOT have time to move out of the way. 

Some survival tips at the above link.

USA UNITS:

Maths of a Car Used as a Weapon

If you are  28  ft away from a car travelling at 35 mph you do not have time to move out of the way.

Some survival tips at the above link.

Stay safe in 2018.

Cheers

Mathspig

h1

4. Too many different ways to do the same thing

October 11, 2017

The Complaint:…………………………………………………………

Too many different ways to do the same thing

………………………………………………………………………………………….

The Cause:……………………………………………………………….

Often, students , who are struggling with a concept, find it even more challenging when changing grades and/or schools because a new teacher uses a different method to the one they were taught.

eg. Long Division must have the most ridiculous number of methods for doing it.

Add a multi-cultural classroom and even more confusion results.

More maths news from around the world here.

eg. 2  Expand double brackets

1. X-multiply Method

This is the Method Mathspig taught students long, long ago.

2. Standard Method

Video tutorial from Me vs Maths here.

3. Grid Method

Video tutorial from 3 min Maths here.

The Solution:

Find the method that works for you. Stick with it and practice, practice, practice.

eg. Long Division

Here is the BEST EVER long division method

THE LEGO ARGUMENT:

It would be tragic IF  Lego blocks only had one solution. That is IF 6 Lego blocks could only be arranged in one way. In fact, the number of possibilities of arranging 6 blocks is MIND EXPLODING!

h1

5. It’s Too Hard

September 29, 2017

The Complaint:  

It’s too hard!………………

………………………………………………………………………….

The Cause:

This response often results when students face some new topic – often beyond numbers – that students can’t handle on auto pilot. Instead of working through the problem, they crash and burn.

………………………………………………………………………….

The Solution: 

I’m going to tell you a story. Bear with me for a minute. You did maths from Grade 1 to 6. You’re cool. No major dramas. Then something happens. A new topic, perhaps. Or a new teacher and a new topic. You don’t get it. You sit there looking confused. And then you do this. You say ‘I can’t do maths’( See post here) or ‘It’s too hard’.

In my maths teacher days terror topics were:

Long division

Algebra

Dividing Fractions

Geometry (because so few students listen to what the teacher is saying.)

Trigonometry (Lot of, you know, things to learn. Equations and stuff.)

So you stop doing maths. You retire at the age of, maybe, 13 years.

If you hit the MATHS WALL, here’s what you have to do. Back up a bit. Do some warm up maths on the topic. It’s out there.

eg. The Kahn Academy. I’m not saying it is easy. (See THE MATHS SPEECH here) I’m telling you it is doable. Practise.

Maths is always TOO HARD when you give up. But when you try amazing things can happen.

Besides, if a raccoon can do it.

Here is an exercise that you didn’t think you could do. But it is entirley doable by Middle School students with patience.

Karate Maths of OUCH! That hurts!