Doppler shifted hydrogen absorption lines are seen in the spectrum of a star.
the hydrogen line at 656.28 nm is seen to be shifted to 656.08 nm.
how fast is the star moving (note: the speed of light is approximately 300,000 km/s, or 3 × 105
km/

a) about 1,000 km/s
b) about 1,000,000 km/s
c) about 100 km/s
d) about 10,000 km/s

What is the difference between electrically neutral objects and electrically charged objects

What statements accurately describe atoms

Ablock of mass m = 2.5 kg is attached to a spring with spring constant k = 710 n/m. it is initially at rest on an inclined plane that is at an angle of θ = 23° with respect to the horizontal, and the coefficient of kinetic friction between the block and the plane is μk = 0.19. in the initial position, where the spring is compressed by a distance of d = 0.16 m, the mass is at its lowest position and the spring is compressed the maximum amount. take the initial gravitational energy of the block as zero. a) what is the block's initial mechanical energy? b) if the spring pushes the block up the incline, what distance, l, in meters will the block travel before coming to rest? the spring remains attached to both the block and the fixed wall throughout its motion.