A student in a lab holds an iron nail over an open flame, and no reaction occurs. The nail is then filed, creating small pieces of iron shavings. These pieces burn brightly when placed over an open flame.
Which statement accurately identifies one of the changes that occurs as a physical or chemical change?

Formation of small pieces of iron shavings is a physical change whereas burning of pieces of iron shavings is chemical change.

Formation of small pieces of iron shavings is an example of physical change because it can be changed again into nail while on the other hand, burning of pieces of iron shavings on the flame is an example of chemical change because it can't change again into its original shape. Physical change is a change in matter which does not change the chemical properties of the matter whereas chemical change is a change in matter which change the chemical properties of the matter.

relative humidity is a measure of the amount of moisture in the air relative to the total amount of moisture the air can hold.

so d

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