How is 'one standard kilogram' defined in SI system?

When a moon is just a shadow and looks like no moon at all

What do scientists call water

Assume that the amplifiers on the stage operate at a combined power of 5,000 Watts, and that 80% of this is converted to sound. Which of the following best approximates the fraction of this power incident upon each eardrum onstage?

How does an open parachute increase the air resistance of a falling skydiver

The first element on the periodic table is Answer here

A person holds onto an object for 2 minutes, but doesn't move the object. Is work done on the object?

Which two vectors add together to give a resultant with the smallest magnitude, and which two vectors add to give a resultant with the largest magnitude? in each case specify the magnitude and direction of the resultant?

The largest velocity reached by a falling object is its

Shows a 190 g hamster sitting on an 820 g wedge-shaped block. the block, in turn, rests on a spring scale. an extra-fine lubricating oil having μs=μk=0 is sprayed on the top surface of the block, causing the hamster to slide down.

What will happen to the hydronium ion concentration and pH of the water if hydrochloric acid is added to water?