Which of these is the best definition of a fuel cell?

The critical angle for a transparent material is the angle at and beyond which all light within the material is:

One end of a rope is tied to the handle of a horizontally-oriented and uniform door. a force fis applied to the other end of the rope as shown in the drawing. the door has a weight of 145 n and is hinged on the right.

Suppose a wheel with a tire mounted on it is rotating at the constant rate of 2.27 times a second. A tack is stuck in the tire at a distance of 0.393 m from the rotation axis.

What is the measure of a change in an object's velocity? (this is all it asks, no answer choices)

What do scientists mean by the word Theory? A. An uncertain idea. B. An obsolete idea C. An idea which allows you to try to predict future events D. An idea which cannot be checked. so although it may sound convincing, we need to keep an open mind

Which wave A or B has a higher energy

What does the law of conservation of energy state about energy in a closed system?

James joule carefully measured the difference in temperature of the water at the top and bottom of a waterfall. Why did he expect a difference

To change gross income, someone would need to? save more per month. reduce deductions. earn more money. increase withholdings.

An elevator (mass 4150 kg) is to be designed so that the maximum acceleration is 0.0800g. what is the maximum force the motor should exert on the supporting cable?