In order for a reaction to begin, what is required?

activation energy

ionic bonding

precipitate forming

bubbling

Dos pelotas de tenis se lanzan verticalmente, hacia arriba y desde el mismo punto, con 2 s de diferencia. La velocidad inicial de la primera es de 20 m/s, y la de la segunda, de 30 m/s.

What distinguishes the measurement of speed from that of velocity and acceleration?

Which statement describes the magnetic field within a bar magnet?

A 0.0414 kg ingot of metal is heated to 243◦C and then is dropped into a beaker containing 0.411 kg of water initially at 18◦C. If the final equilibrium state of the mixed system is 20.4◦C, find the specific heat of the metal.

The higher the density the heavier it is

A geologist finds ripples preserved in ancient sedimentary rock that look just like ripples made by water in mud. He concludes that there was once water in that location that created the ripples. Why is this conclusion reasonable?

In science what is the requirement of doing work?

What Fitness Gram test is assessing your cardiovascular endurance?

A graph titled Position versus time for with horizontal axis time (seconds) and vertical axis position (meters). A straight blue line runs with an upward slope from 0 seconds 3 meters to 4 seconds 15 meters. The starting position of this object is m.

There is a 50 g sample of Ra-229. It has a half-life of 4 minutes. How much will be left after 12 minutes?