A landing craft of mass 12,000 kg prepares itself for a moon landing. When at a

Question

A landing craft of mass 12,000 kg prepares itself for a moon landing. When at a verticle distance of 160m above the surface of the moon its downward velocity is 15m/s-1. A retro-rocket is fired to give the spaceship an upward thrust to clow its speed to zero as it meets the surface.

Calculate the needed thrust to decelerate the crafts initial downward velocity to zero as it lands.

The value for gravity on the moon is g/6. where g = 9,81m/s2

Use a diagram to illustrate the above. A diagram is very important.

Thank you!

Will give excellent feedback if I receive a decent response...

Explanation / Answer

Alright, again, I will walk you through the stages but I'm not drawing a diagram. First, let's put a number on g/6 = 1.63333 v0 = -15 m/s We need to find 'thrust' aka acceleartion v = at + v0 v = at - 15 0 = a*t - 15 ^^But we don't know a/t. THIS A IS DIFFERENT FROM GRAVITY ON MOON We want this to happen as the space thing lands y(t) = 1/2*a*t^2 + v0t -160 = 1/2*(9.8/6)*t^2 - 15t t = 7.557 0 = at - 15 0 = a*7.557 - 15 a = 1.984

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