An electric bulb rated 220V, is connected to 220V, 5Hz AC source. Then the bulb:
(a) Does not glow
(by Glows intermittently
(c) Glows continuously
(d) Fuses

What is the role of the ocular lens?

Could we see a galaxy that is 20 billion light-years away?

Aspring is used to stop a 50-kg package which is moving down a 20º incline. the spring has a constant k = 30 kn/m and is held by cables so that it is initially compressed 50 mm. knowing that the velocity of the package is 2 m/s when it is 8 m from the spring and neglecting friction, determine the maximum additional deformation of the spring in bringing the package to rest.