Energy is required to change the phase of a substance, such as the energy to break the bonds between molecules in a block of ice so it may melt.
During a phase change energy my be added or subtracted from a system, but the temperature will not change. The temperature will change only when the phase change has completed.
The heat Q required to change the phase of a sample of mass m is given by
Q
=
mL
f
(melting or freezing) and
Q
=
mL
v
(evaporating or condensing), where Lf and Lv are the latent heat of fusion and the latent heat of vaporization, respectively.
Key Terms
latent heat of fusion: the energy required to transition one unit of a substance from solid to liquid; equivalently, the energy liberated when one unit of a substance transitions from liquid to solid.
latent heat of vaporization: the energy required to transition one unit of a substance from liquid to vapor; equivalently, the energy liberated when one unit of a substance transitions from vapor to liquid.
sublimation: the transition of a substance from the solid phase directly to the vapor state such that it does not pass through the intermediate, liquid phase
Explanation:
It is given that,
Mass of the rocket,
(a) The SI unit of mass is kilogram (kg). The relation between slugs and the kg is given by :
1 slug = 14.59 kg
So,
Mass of the rocket, m = 3647500 kg
(b) Weight of the rocket is given by :
W = m g
or
(c) If the rocket is placed on the moon. The acceleration due to gravity on the moon is,
Mass is the amount of matter contained inside the object. So, the mass of the rocket remains the same i.e. 3647500 kg
Weight of the rocket on the moon is,
W = 5872475 N
or
Hence, this is the required solution.
Answer:
(C) because the elevator is not accelerating
Note F = M a = M g (the resultant force on the elevator is due to gravity)
or Fup = Fc the force exerted on the elevator by the cable
and Fdown = Fe the force exerted on the elevator by gravity
F = M a = Fup - Fdown = zero resultant force on elevator
The evidence that the universe is expanding comes with something called the red shift<span> of light. Light travels to Earth from other galaxies. As the light from that galaxy gets closer to Earth, the distance between Earth and the galaxy increases, which causes the wavelength of that light to get longer.</span>