G-Force

Yu Weiran(33) 1A3

What is G-force?

• Short term for Gravitational Force

• Is experienced by an object due to the vector sum of non-gravitational forces

• Causes stresses and strains on objects if travelling at a high speed

• SI unit: m/s2

Measurement

• Measured using accelerometer

accelerometer

Accelerometer

• Is a device which measures proper acceleration• Can be single or multi axis• Can be used to measure vehicle acceleration,

vibration on cars, machines, buildings, process control systems and safety installations,

• Can also be used to measure seismic activity, inclination, machine vibration, dynamic distance and speed with or without the influence of gravity

Calculation

• Acceleration = v2 / r • Eg: Speed of car=230 mph is 337 feet per second (f/s). • (337 f/s)2 / 750 feet = approximately 151 f/s2. • The acceleration due to gravity (1 G) is 32 f/s2. • 151 / 32 = 4.74 Gs experienced by the driver

Effect of G-force to human

• Negative G force (braking) may cause retinal detachment

• Too much G force may cause dizziness to the driver

• Positive G force (acceleration) will push the blood in your body towards your feet and resist your heart's attempts to pump it back up to your brain

• You will begin to get tunnel vision, then things will lose color and turn white, and finally everything will go black.

G-force Table

• Ultracentrifuge 300,000 G • Baseball struck by bat 3000 G • Soccer ball struck by foot 300 G • Car crash (100 km/h into wall) 100 G • Braking of car 0.8 G • Parachutist during opening of parachute 33 G • Gravity on surface of Sun 27 G • Gravity on surface of Earth 1 G • Gravity on surface of Moon 0.17 G

References

• Car Science by Richard Hammond• Fifth Gear S16E2• http://en.wikipedia.org/wiki/G-force• http://www.wisegeek.com/what-is-g-force.htm

• http://hyperphysics.phy-astr.gsu.edu/hbase/carcr2.html• http://en.wikipedia.org/wiki/Accelerometer• http://www.electronicaviation.com/articles/General/142

• http://csel.eng.ohio-state.edu/voshell/gforce.pdf