Amixture of very finely ground iron particles and sand particles could best be separated in lab by: a magnet adding water and filtering the metals comparing their boiling points comparing their melting points

Answer is: a magnet.

1) A magnet is attracted to magnets (ferromagnetic), sand is not.

2) Iron and sand do not dissolve in water, so if they are filtered, both substances will stay on filter paper.

3) Iron (Fe) and sand (SiO₂) boiling points are very close, around 1900°C.

4) Iron and sand melting points are very close, around 1550°C.

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