an engineer places a small sample of a material on a horizontal disk whose surface is made of another material and then rotates the disk from rest with a constant angular acceleration of 4 rad/s2. assuming that the coefficient of static friction between the sample and disk is 0.2, what is the angular velocity of the disk at the time instant when the sample starts slipping on the disk?

c.the charges if the proton and electron and gravity

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2

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.