I've got a test tomorrow morning help! A 100.0 W incandescent light bulb emits about 1.6 J of energy as useful, visible light each second. What is its efficiency?

A23 kg log of wood begins from rest, 300 m up a sluice (a water track used to transport logs, think of it as an inclined plane with negligible friction) inclined at 20° to the horizontal. after it reaches the flat waterway at the bottom it collides elastically with a 100 kg block of wood initially at rest near the base of the incline. (a) how long does it take the 23 kg log to travel down the incline? (b) what is the speed of the 23 kg log at the bottom of the incline? (c) what are the velocities of both blocks of wood after the collision? (d) what is the total kinetic energy before the collision? (e) what is the kinetic energy of the 23 kg log after the collision? (f) what is the kinetic energy of the 100 kg block of wood after the collision? (g) what is the total kinetic energy after the collision? (h) compare the total initial and total final kinetic energies. is this consistent with what you would expect for elastic collisions? explain!

An incident ray through the focal point of a spherical mirror will: reflect through the center of curvature. reflect back through the focal point. reflect parallel to the principle axis. reflect the same direction as the incident ray.

4. a 75.0 g piece of ag metal is heated to and dropped into 50.0 g of water at the final temperature of the mixture is what is the specific heat capacity of silver? 5. a 465 g chunk of iron is removed from petrucci, ralph h.. general chemistry (p. 290). pearson education. kindle edition.