Write Newton's 3rd law. How would this law relate to a rocket ship taking off from the earth? Would this law affect the rocket s
1 answer:
Answer:
Part A
Newton's 3rd law states that action and reaction are equal and opposite, mathematically, we have;
= -
Where;
= The action force
= The reaction force
Part B
The law indicates that the force with which a rocket ship uses in taking off from the Earth, is equal in magnitude, and opposite in direction to the reaction force of the Earth to the motion of the rocket, (-)
Part C
The law is a universal law, and it will also affect the rocket ship in space, as the force of the jet from the exhaust is directed towards Earth while in space, the rocket is propelled deeper into space
Explanation:
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Answer:
A fan with an energy efficiency of 30 % would need 62.5 watts to bring a desired volume flow of 0.05 cubic meters per second through a cross-sectional area of 20 square centimeters.
Explanation:
Complete statement is: <em>Determine the power that needs to besupplied by the fan if the desired velocity is 0.05 cubic meters per second and the cross-sectional area is 20 square centimeters.</em>
From Thermodynamics and Fluid Mechanics we know that fans are devices that work at steady state which accelerate gases (i.e. air) with no changes in pressure. In this case, mechanical rotation energy is transformed into kinetic energy. If we include losses due to mechanical friction, the Principle of Energy Conservation presents the following equation:
(Eq. 1)
Where:
- Efficiency of fan, dimensionless.
- Electric power supplied fan, measured in watts.
- Rate of change of kinetic energy of air in time, measured in watts.
From definition of kinetic energy, the equation above is now expanded:
(Eq. 2)
Where:
- Density of air, measured in kilograms per cubic meter.
- Volume flow, measured in cubic meters per second.
- Cross-sectional area of fan, measured in square meters.
If we know that ,
,
and
, the power needed to be supplied by the fan is:
A fan with an energy efficiency of 30 % would need 62.5 watts to bring a desired volume flow of 0.05 cubic meters per second through a cross-sectional area of 20 square centimeters.