Pl will give select all the signs of a chemical change from the list below. (you may need to select more than one for full points) evaporating bubbles (gas formation) color change dissolving

The formation of bubbles and a colour change are signs of a chemical change.

One of the substances must have evolved the gas and changed into something else.

One of the substances must have changed into something else with a different colour.

Both above are chemical changes.

Evaporation and dissolving are physical changes, because the substances do not change their chemical structure in the process.

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j

some sources quote the lethal dose, for an average 170lbs opiate-naive individual is between 75 and 375 mg