an introduction to acceleration: more practice

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An Introduction to Acceleration: More Practice

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Page 1: An Introduction to Acceleration: More Practice

An Introduction to Acceleration: More Practice

Page 2: An Introduction to Acceleration: More Practice

An Introduction to Acceleration: More Practice

Page 3: An Introduction to Acceleration: More Practice

An Introduction to Acceleration: More Practice

Page 4: An Introduction to Acceleration: More Practice

An Introduction to Acceleration: More Practice

Page 5: An Introduction to Acceleration: More Practice

An Introduction to Acceleration: More Practice

Page 6: An Introduction to Acceleration: More Practice

An Introduction to Acceleration: More Practice

Page 7: An Introduction to Acceleration: More Practice

An Introduction to Acceleration:More Practice

Page 8: An Introduction to Acceleration: More Practice

An Introduction to Acceleration: More Practice

Page 9: An Introduction to Acceleration: More Practice

Gravity and Free-Fall: Student Learning Goals

Students will conduct an inquiry to measure gravitational acceleration, and calculate the percentage error of their experimental value (B2.3, B2.10)

Page 10: An Introduction to Acceleration: More Practice

Gravity and Free-Fall

SPH4C

Page 11: An Introduction to Acceleration: More Practice

g

The acceleration due to the Earth’s gravity is

9.8 m/s2 [down].

The magnitude of this acceleration is denoted by the letter g.

132

Page 12: An Introduction to Acceleration: More Practice

Up, then Down

An object feels this acceleration when travelling up (when it slows them down) and when travelling down (when it speeds them up).

Page 13: An Introduction to Acceleration: More Practice

Mass doesn’t matter

Note that all objects, regardless of mass, experience the same acceleration.

Page 14: An Introduction to Acceleration: More Practice

Galileo

This discovery is attributed to Galileo.

http://www.youtube.com/watch?v=5C5_dOEyAfk

Page 15: An Introduction to Acceleration: More Practice

Drag

However, some objects are slowed by atmospheric drag more than others.

Page 16: An Introduction to Acceleration: More Practice

Terminal velocity

At a given speed, the drag will equal the gravity, and the object will stop accelerating, i.e. reach “terminal velocity.”

Page 17: An Introduction to Acceleration: More Practice

Terminal velocities

Typical terminal velocities:

Human 53 m/s (190 km/h)

Human with parachute 5 m/s (18 km/h)

Dandelion seed 0.5 m/s (1.8 km/h)

Page 18: An Introduction to Acceleration: More Practice

The fastest man

On August 16th, 1960 U.S. Air Force Captain Joe Kittinger broke the sound barrier (1240 km/h) during a free-fall from the high altitude balloon Excelsior III, at an altitude of approximately 31 km.

Page 19: An Introduction to Acceleration: More Practice

Highest fall survived (without a parachute)

Flight attendant Vesna Vulovič fell 10,000 m on January 26, 1972 when she was aboard a plane that was brought down by explosives over the Czech Republic.

She suffered a broken skull, three broken vertebrae (one crushed completely), and was in a coma for 27 days, but she survived!

Page 20: An Introduction to Acceleration: More Practice

g’s

Accelerations are often given in terms of g.

For example,

4 91

9 852

2

ms m

s

gg

.

Page 21: An Introduction to Acceleration: More Practice

Blackout

A typical person can handle about 5 g before loss of consciousness, “blackout,” occurs.

The record for the most g forces on a roller coaster belongs to Mindbender at Galaxyland Amusement Park in Edmonton, Alberta, at 5.2 g.

Page 22: An Introduction to Acceleration: More Practice

Greyout

Through the combination of special g-suits and efforts to strain muscles —both of force blood back into the brain— modern pilots can typically handle 9 g or more.

They may experience a “greyout” (temporary loss of colour vision, tunnel vision, or an inability to interpret verbal commands) between 6 and 9 g.

Page 23: An Introduction to Acceleration: More Practice

Negative g’s

Resistance to "negative" or upward g’s, which drive blood to the head, is much less (typically in the -2 to -3 g range).

During “redout,” vision goes red, probably due to capillaries in the eyes bursting under the increased blood pressure.

Page 24: An Introduction to Acceleration: More Practice

“g-Force”

Acceleration perpendicular to the spine is more tolerable.

Acceleration pushing the body backwards (“eyeballs in”) is tolerable up to 17g, and pushing the body forwards (“eyeballs out”) up to 12g.

Page 25: An Introduction to Acceleration: More Practice

Strongest g-forces survived

Voluntarily: Colonel John Stapp in 1954 sustained 46.2 g in a rocket sled, while conducting research on the effects of human deceleration

Page 26: An Introduction to Acceleration: More Practice

Strongest g-forces survived

Involuntarily: Formula One racing car driver David Purley survived an estimated 178 g in 1977 when he decelerated from 173 km/h to 0 in a distance of 66 cm after his throttle got stuck wide open and he hit a wall

Page 27: An Introduction to Acceleration: More Practice

Everyday g-forces

Coughing: 3.5 g

Sneezing: 2.9 g

Page 28: An Introduction to Acceleration: More Practice

Free fall

Objects in free-fall feel

0 g, or “weightlessness.”