Please PLEASE HELP ASAP A student placed four objects on a plastic tray: a rock, an eraser, a wood block, and an ice cube. The student slowly lifts the tray and measures the height at which each object begins to slide in order to compare the friction of each object. The table above shows the results. In a separate experiment the student used the same objects and tray, but glued a piece of gritty sandpaper to the tray. What results would be expected? A) The items would slide faster at the same heights. B) The items would start to slide when the tray is not lifted as high. C) The items would not slide at all, no matter how high the tray is raised. D) The tray would need to be raised higher before the items start to slide.

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!

Dao makes a table to identify the variables used in the equations for centripetal acceleration. what quantities belong in cells x and y?

A10 kg box initially at rest is pulled 18 meters across a horizontal, frictionless surface by a 40 n force. what is the block’s final velocity over the 18 meters?