question archive Arizona State UniversitySES 141 1) A mass is a fixed quantity of matter
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Arizona State UniversitySES 141
1) A mass is a fixed quantity of matter. The weight that mass feels depends on the __________ acting on the mass.
2) What is the approximate energy density (in MJ/kg) of natural gas?
3) What is the approximate energy density (in MJ/kg) of olive oil?
4) A speed divided by a time is called an ____________.
Answer:
1) A mass is a fixed quantity of matter. The weight that mass feels depends on the gravity acting on the mass.
- Objects with more mass have more gravity. Gravity also gets weaker with distance. So, the closer objects are to each other, the stronger their gravitational pull is. Earth's gravity comes from all its mass.
2) What is the approximate energy density (in MJ/kg) of natural gas? 55 MJ/kg
3) What is the approximate energy density (in MJ/kg) of olive oil? 40 MJ/kg
- Energy density is the amount of energy that can be stored in a given mass of a substance or system. The higher the energy density of a system or material, the greater the amount of energy stored in its mass. Energy can be stored in many different types of substances and systems.
Gravimetric energy density (Specific energy) is one way to express energy density which tells how much energy a system contains in comparison to its mass; typically expressed in watt-hours per kilogram (Wh/kg), or Megajoules per kilogram (MJ/kg)
4) A speed divided by a time is called an velocity.
- Velocity (v) is a vector quantity that measures displacement (or change in position, Δs) over the change in time (Δt), represented by the equation v = Δs/Δt. Speed (or rate, r) is a scalar quantity that measures the distance traveled (d) over the change in time (Δt), represented by the equation r = d/Δt.