While hauling a log in the back of a flatbed truck, you are pulled over by the state police. Although the log can't roll sideways, the police claim that the log could have slid out the back of the truck when accelerating from rest. You claim that the truck couldn't possibly accelerate at the level needed to achieve such an effect. Regardless, the police write a ticket anyway and now your day in court is approaching. The log has a mass of m = 829 kg; the truck has a mass of M = 9150 kg. According to the truck manufacturer, the truck can accelerate from 0 to 55 mph in 22.0 seconds, but this does not account for the additional mass of the log. Calculate the minimum coefficient of static friction ?s needed to keep the log in the back of the truck. According to the scientific literature, the coefficient of static friction between the log and the trailer bed should be roughly 0.840. Given this fact, select the correct A) There is little chance the log could have slid out the back. B) The police officer is correct. The log posed a real danger. C) The results are not conclusive.

graphing motion: mastery test

209be

what is the instantaneous acceleration of

the particle at point b?

0 meters/second?

10 meters/second?

12 meters/second?

velocity imetersisecond

15 meters/second?

20

time (seconds)

answer: 0 meters/second^2

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

the aurora is formed when charged particles emitted from the sun during a solar flare penetrate the earth's magnetic shield and collide with atoms and molecules in our atmosphere. these collisions result in countless little bursts of light, called photons, which make up the aurora.

auroras are generated by charged solar particles hitting molecules in earth's atmosphere. this usually happens in high latitudes, because our planet’s magnetic field tends to funnel these particles toward the poles. that’s why it can be experienced in northern ohio.