Recent findings in astrophysics suggest that the observable universe can be modeled as a sphere of radius r = 13.7 × 109 light-years = 13.0 × 1025 m with an average total mass density of about 1 × 10-26 kg/m3. only about 4% of total mass is due to "ordinary" matter (such as protons, neutrons, and electrons). part a estimate how much ordinary matter (in kg) there is in the observable universe.

To do work, this truck uses energy stored in chemical fuel and an electrical battery. how much total energy does this truck put out?

Which statement correctly describes the relationship between frequency and wavelength?

On a frictionless air track, a blue glider with mass 0.200 kg is moving to the right with a speed of 8.00 m/s. it strikes a red glider that has mass 0.600 kg and that is initially at rest. after the collision, the blue glider is moving to the left with a speed of 3.00 m/s.(a) what are the magnitude and direction of the velocity of the red glider after the collision? (b) is this collision elastic?