Keiran, whose mass is 45 kg, is riding his 5.0 kg skateboard down a level, horizontal sidewalk with a constant speed of 6.0 m/s when he rolls across a 5.0-m-long patch of sand on the pavement. The sandy pavement provides a force of friction of 6.0 N. How much work is done by the patch of sandy pavement on the skateboarder? (As with this and all work-out questions, remember to work symbolically first to be eligible for full credit.)

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.

the doppler effect is used by weather forecasters to measure 

moving clouds