A rocket produces a total thrust of 20,000 N. If the mass flow rate of propellants is 16 kg/s, what will be effective exhaust velocity?

625 m/s

1250 m/s

2500 m/s

5000 m/s

Correct Answer : 1250 m/s

Explanation : Total Thrust = mass flow rate x effective exhaust velocity. Here we assume that the mass flow rate is constant, flow is axially directed and frictional effects are neglected.
So, 20,000 = 16 x u_eff
u_eff = 20,000/16 = 1250 m/s.

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In which of the propulsion systems is the maximum temperature achieved?

Nuclear

Chemical

Arc heating

Solar heating

Correct Answer : Option (C) : Arc heating

Explanation : Arc heating can lead to temperatures of about 20,000 deg C. Chemical propulsion systems have a maximum temperature ranging from 2500-4100 deg C, while nuclear fission leads to temperatures of about 2700 deg C.

What is the propulsion duration of resistojets?

Few weeks

Few days

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Correct Answer : Option (B) : Few days

Explanation : Resistojets have a propulsion duration spanning a few days. The chemical rocket engines have a propulsion duration lasting a few seconds to a few minutes, while for ion-electrostatic engines, it lasts for months.

Which of the following engines can achieve the maximum specific impulse of 5000 s?

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Correct Answer : Option (B) : Ion-electrostatic

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