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A
skateboarder drops into an empty swimming pool from the deck. He is 5' 10"
tal when standing on his board. He rides the board down to the bottom of the
pool and up the other side. As he reaches the top of the other side he
crests the lip and goes back down into the pool.
The next day at school he braggs to his
friend that he jumped 6' over the deck on one of his stunts.
Consider the following questions: |
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1. Is he telling the truth? Why?
2. How high is the most he could possibly
jump? Why?
3. How fast is he going at the bottom of
the 3 meter deep pool?
3. How could he increase how high he
can jump?
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A freestyle
MX rider is doing jumps in a stadium. In the distance provided to accelerate
up to the jump he is able to reach 110 km/hr (72 mph). While doing a can-can
stunt, at the peak of his jump, his vertical speed is 0 and his forward
speed is just 10 km/hr. His mass is 80 kg and his bikes is 120 kg.
Consider the following questions: |
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1. How high was he while doing the Can-Can
jump?
2. If he could get up to 1
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Shuttle Astronaut and the Satellite
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A
shuttle astronaut is in the cargo bay preparing to repair a satellite. The
satellite is quite massive and the shuttle and the satellite are in the same
orbit. The shuttle has maneuvered itself right next to the satellite and has
synchronized its orbital velocity with that of the satellite.
Consider the following questions, answer the
ones you can. When there is not enough information state that. |
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1. What is
the satellite's momentum? What is the satellite's kinetic energy?
with respect to the earth? with respect to
the astronaut/shuttle?
2. What happens when the astronaut grabs
the satellite with his hands?
3. How much work does it take the
astronaut to position the satellite in its docking position near the bracket
in the cargo bay when its is 2 meters to its side? 2 meters closer to the
earth below the bracket ( note the shuttle orbits upside down with the cargo
bay opening to the earth |
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Gearhead Gary has a
1968 Goat (GTO) with a 396 big block. He says it produces a maximums of 450
horsepower at 6,750 RPM and has 500 lb-ft of torque at 3,500 rpm. It
also has a curb weight of 4,200 pounds with a half tank of gas and him in
the driver's seat.
He claims he can
do a quarter-mile drag race in 11 seconds flat. He also said he once had it
going over 150 miles per hour on a 5 mile long flat road out in the desert.
Consider the
following questions |
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1.He starts the car up
and revs it up, first to 3,500 rpm, and then to 7,750 rpm with the
transmission in neutral. How much horsepower is the car making? how much
torque?
2. You have run your Nitrous
equipped Honda at the drag strip and were clocked doing the quarter-mile in
12.3 seconds. He wants to drag race you for pink slips, winner-take-all.
Should you do it? |
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A
snowboarder drops into a half-pipe from position (A). He crosses the
half-pipe and attempts to do a 360 as he crests the lip at position (B), 10
meters lower in elevation. It takes him .5 seconds to complete the spin part
of his 360. His mass with his equipment is 100 kg.
Consider the following questions: |
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1. What is his potential
energy before he drops in?
2.
How much air does he get?
does it make a diference if he spreads out with his hands above his head
2. Does he make the
complete 360 in the air?
Instead of crossing
the pipe to the other side he goes straight down it to the bottom
without turning.
3.
When he plows into the
people in the lift line (C) at the bottom of the hill, 150 meters lower in
vertical elevation, what is the maximum speed he could be going? kinetic
energy? |
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An downhill speed skier
plummets down a mountain in the Andes. The vertical elevation of the
mountain is 4,000 meters above sea level. The slope flattens out at an
elevation of 3,000 meters. His mass with skis is 120 kg.
The world record for speed skiing is 250
km/hr (154 mph).
Consider the
following questions: |
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1.
Can he break the record?
2. What is the fastest he
could be going when the slope flattens out?
3. How high would the
slope have to be for him to have a chance at the record? |
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http://hektor.umcs.lublin.pl/~jkisyn/Skipage/Flakes/Speed/Speed.htm
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An in-line skater, a
skate-boarder and a BMX bicycle rider are doing stunts in an empty swimming
pool.
They have hung a ribbon above the edge of
the opposite side of the pool. If standing on the pool deck right next to
where it the ribbon is hung it is just out of reach to all three of them.
They now take turns dropping into the pool
from the deck and trying to grab the ribbon with one hand. The BMXer pedals
on the way down and the blader skates while the skate-boarder just rides.
Consider the
following questions: |
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1. Can any one of them
actually grab the ribbon? all of them? none of them? Why?
2. Who has the best chance of actually
grabbing the ribbon? Why?
3. Who has 2nd best chance? the worst
chance? Why?
4. You now find out that the skateboard
has a heavy lead ballast attached to it, making its mass 50 kg. Does that
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Street Luge
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friction on planet Nodrag) |
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A downhill street luge racer starts from a position
that is 150 meters higher in elevation than where you are standing next to
the course.
Just at the moment he passes by your position he loses
control and tumbles down the road, finally hitting the hay bales 25 meters
down the track.
Consider the following questions: |
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1. What would be worse, his crash, or stepping out of a car
on the freeway at 80 Km/hr.
2. How fast was he going when he lost control
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