Friday, June 27, 2014
What happens when an aircraft breaks the sound barrier?
Mar 11, 2002.
What happens when an object breaks the sound barrier must begin with the description of sound as a wave. Anyone who has heard an echo (sound waves reflecting off a distant surface) or been far enough away from an event to see it first and then hear it, is familiar with the reasonably slow travel of sound waves. At sea level and temperatures of 22 degrees Celsius, sound waves travel at 345 meters per second. As the temperature decreases, the sound speed also decreases, so for a plane flying at 35,000 feet (10688 metres) where the temperature is around -55 degrees Celsius, the speed of sound is 295 meters per second.
When the sources of a sound is moving it can begin to catch up with the sound waves they emit. As the speed of the object increases to the speed or velocity of sound waves, these sound waves begin to pile up in front of the object. If the object has sufficient acceleration, it can burst through this barrier of sound waves and move ahead of the sound it is making. As the object outruns all the pressure and sound waves in front of it, it is heard on the ground as an explosion, or sonic boom.
At supersonic speeds (those greater than the speed of sound), there is no sound heard as an object approaches an observer because the object is traveling faster than the sound it produces. Only after the object has passed will the observer be able to hear the sound waves emitted from the object.
Aircraft wings create low-pressure regions. Under sonic flight conditions the lowered pressure condenses the water in the air, creating a vapour cloud. Just as the aircraft bursts through the sound barrier, the air is locally disturbed by the resulting shock wave and the condensation/vapour cloud disappears.
Explain how there can be slight variation in the speed of sound? In hot temperatures, sound travels travels at 345 metres per second but in cold temperatures, sound travels in a different speed which is 295 metres per second.
What is an echo? An echo is sound waves reflecting off a distant surface and then travels back to the listener.
What happens to the sound waves, when the object making the sound is moving? The sound waves begin to pile up in front of the object.
Why is there no sound heard as an object approaches if it is going at supersonic speed?
Because the object is moving faster than the sound it produces.
What does supersonic mean? Supersonic is those greater than the speed of sound.
What does decrease mean? Decrease means to make or become smaller or fewer in size, amount, intensity or degree.
Sufficient? Private income.
Emit? Gas or radiation.
Velocity? A speed of something in a given direction.
Condense? Something density or more concentrated.
Acceleration? A vehicle capacity to gain speed.
Kiwi kids news - Week 8
1. In which of the following countries has a major conflict started after ISIS militants took over the city of Mosul?
• a. Morocco
• b. Iraq
• c. Somalia
2. True or false, John Key has publicly stated that New Zealand supports the United States’ latest military action in Iraq? True
3. Which country won the last football World Cup?
• a. Italy
• b. Brazil
• c. Spain
4. Which of the following countries have announced that they will cut carbon emissions by 30% by 2030 to combat global warming?
• a. New Zealand
• b. United States
• c. China
5. A food drop was made to help a man in his efforts to cross the Tasman Sea. How is he traveling from Australia to New Zealand?
• a. paddling a surfboard
• b. swimming
• c. kayaking
• d. rowing
6. The Iguazu Falls are some of the world’s largest and have just recorded their biggest
ever flows. In what part of the world are the Iguazu Falls located?
• a. Africa
• b. Asia
• c. South America
7. Astronomers studying how the universe started have detected the oldest light it is
possible to observe in space. What is the name of the theory that scientists believe
created the universe?
• a. Big Bang Theory
• b. Universal Expansion Theory
• c. Black Hole Theory
8. The Westpac Rescue Helicopter was sent to the Canterbury coast after sightings of a plane in the water. What did the crew find when they got there?
• a. a Google wifi balloon
• b. a homemade submarine
• c. another rescue helicopter that had crashed in the water
9. In which UK city will the Commonwealth Games start next month? Scotland
10.Michael Schumacher has been released from hospital in France after a skiing
accident in December. In which sport was Michael Schumacher a famous competitor?
• a. Skiing b. Motor Racing c. Football
11.What was thought to responsible for a series of loud bangs and thumps that were felt
across Auckland city last Thursday?
• a. Volcanic tremors
• b. A Meteor Shower
• c. Bomb testing
12.An injured German man was finally brought to hospital after emergency workers and
volunteers took 12 days to rescue him. Where was he rescued from?
• a. Fiordland National Park
• b. Mt Everest
• c. A German Cave
13.In which country would you be most likely to see a sombrero?
• a. Mexico b. Spain c. Argentina
14.A list of the most trusted jobs was released last week. Which of the following occupations had the highest level of trust from the New Zealand public?
• a. Firefighters
• b. Police
• c. Nurses
• d. Teachers
15.The Washington Redskins team are being pressured to change their name as it is
offensive to Native American Indians. What sport do the Washington Redskins play?
• a. basketball
• b. American football
• c. ice hockey
Monday, June 23, 2014
Thursday, June 19, 2014
Tuesday, June 17, 2014
Tuesday, June 10, 2014
1. George was driving to Lake Taupo from Auckland. Lake Taupo is 407 kms away from Auckland and he had to do the trip three times a week for work. Assuming there are 4 weeks in a month. How many kms did he drive in total in 1 month? 4884
2. Janine had 17 jars of jelly beans each with with 364 jelly beans inside. How many jelly beans did she have in total? 6188
3. The temperature on Mercury is 206 degrees celsius. However the sun is 14 x that temperature. How hot is the sun? 2884 degrees celsius
4. Jake had $675 to go shopping for his birthday. He shared his birthday money between himself and 2 of his friends, how much money did each of them get? $225
5. Mike had 275mls of milk in his carton. He drank this amount of milk 3 times a week. How much milk does Mike drink in one week? 825
What about two weeks? 1650
A month? 3300
One year? 6600
6. Jane bought two new pairs of shoes every 3 months. How many pairs of shoes did she have after one year? 16 new pairs of shoes
7. The class table was 600cm. The table was shared between 12 students. How many cm of the table did each student have to use? 50 cm each
8. Michael knew that to qualify for the running championships he would need to beat 13.2 seconds to run 150 meters.
Michael ran everyday for one year. How many meters did he run in total? 54750m
What about only six months? 273750
9. Jane knew that her parents would deposit $1.50 per day in to her bank account. How much money was in her account after 3 years?$1642
What about 12 years? 6468
Monday, June 9, 2014
Last week, Maya and Gabriela decided to see how fast they could sprint 400 meters. They asked their friend Jessica to time them with a stopwatch. After 4.72 minutes, Jessica agreed to time the runners. Maya sprinted first and ran 400 meters in 76.39 seconds. When it was Gabriela's turn, she sped off and completed the run in 72.69 seconds.How much faster was Gabriela than Maya in seconds?
Maya ran 76.39
Gabriela ran 72.69
What can you add to 72.69 to make 76.39
72 + 4 makes 76
.3 + .3 = .6
.09 + .00 = 0.9
Answer - 4.30
5 + 4 = 9
.3 + .7 = 1.0
Answer - 10.0
5 + 4 = 9
.3 + .7 = 1.0
.01 + .07 = .08
Answer - 10.08
5 + 0 = 5
.3 + .4 = .7
.01 + .07 = .08
.007 +.000 = .007
Answer - 5.787
53 + 47 = 100
.1 + .8 = .9
Answer - 100.9
5 + 4 = 9
.3 + .7 = 1.0
.01 + .08 = .09
Answer - 10.09
5 + 0 = 5
.3 + .4 = .7
.01 + .07 = .08
.000 + .008 =.008
Answer - 5.788
Kiwi kids news - Week 6
1. Which industry is considered to be the deadliest in New Zealand?
• a. fishing b. forestry c. dairy farming
2. True or false, the Government will introduce a new policy later this month which will require tourists to sit a driving test before being allowed to drive in New Zealand?
3. Which country is facing allegations of bribery after winning the rights to host the 2022 football World Cup? • a. Australia b. Japan c. Qatar
4. What have police announced they will be introducing to combat speeding?
• a. 200 new road patrol officers that will target known speeding areas
• b. new digital speed cameras that will be introduced across the country
• c. a new law allowing them to confiscate cars from drivers who receive more than two speeding fines in a week
5. The Taliban terrorist group released a video showing the return of a captured American soldier to US forces. What did they swap him for?
• a. five Taliban members that were detained by the US
• b. weapons - guns and explosives
• c. two Black Hawk helicopters
6. Who said the following in an interview last week: “Here’s the thing, if we are not in it we will never be in it ever again”?
• a. John Key (politician)
• b. Peter Jackson (movie director)
• c. Grant Dalton (sailor)
7. Why has a Coromandel dairy farmer received a $52,500 fine recently?
• a. discharging effluent into a waterway that flows into a harbour
• b. for not providing enough feed for his animals
• c. using water from a local river from irrigation without council consent
8. True or false, Nigeria has banned protests in the capital by supporters of the 200 kidnapped schoolgirls?
9. How many states does the United States have?
• a. 48
• b. 50
• c. 52
10. Basketball hero Steven Adams returned home to New Zealand last week after his team Oklahoma City Thunder were knocked out of the competition. What food did he say he was craving when he arrived?
• a. a pie
• b. roast lamb
• c. fish and chips