1) the density of gold is 19.3g/cm3. what is the mass of 15 cm3 of gold? 2) You have a graduated cylinder containing 20 ml of water. you add 250 g of lead weights, and the volume of water in the graduated cylinder rises to 42 ml. What is the density of the lead?

3) A drinking glass at a crime scene contains a clear, colourless liquid that may be water or alcohol. As the investigator, you know that the densities of alcohol, water and ice are 0.79g/ml, 1.0 g/ml and 0.92g/ml, respectively. Design a simple method to determine the identity of the mystery liquid. Explain your design.

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