Peter M. answered • 11/28/23
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AP Physics 1 & 2, IB Physics. Engineer with 30 years teaching Physics
This problem can be solved using the Impulse-Momentum relationship:
FΔt = mΔv
Divide both sides by Δt and you have F = (m/Δt) ⋅Δv
(m/Δt) is your mass "flow" rate that is given and Δv is the relative speed of the exhaust gas.
Watch your units.
Peter M.
Mass, m, is measured in kilograms (kg). Time, Δt, is measured in seconds (s). Here it is the 1.0 second in the denominator of the (kg/s). That is where this problem hides that important piece of data. :-) Change in velocity, Δv, assumes that the gas starts from zero and is accelerated to the given velocity. Convert kilometers (km) to meters.
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11/29/23
Taylor P.
Converted km to m. Yet still am getting question wrong. My numbers are 102 kg/s and 2 km/s, 2000m/s. multiplied the two and got 2,040,000. I even tried converting to MN, millinewtons. still got it wrong?
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12/05/23
Peter M.
Taylor, m = 285 kg, Δt = 1 sec, so 285 kg/s. Δv = 10 km/s or 10,000 m/s. MN is Mega Newtons 10^6, not milli Newtons. Not sure where you got 102 kg/s and 2 km/s from. Please explain so I can help with any misunderstanding.
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12/05/23
Christina B.
I dont understand what numbers to plug in11/29/23