Question

Imagine a landing craft approaching the surface of Callisto, one of Jupiter's moons. If the engine provides an upward force (thrust) of 3120 N, the craft descends at constant speed; if the engine provides only 2106 N, the craft accelerates downward at 0.39 m/s2. What is the weight of the landing craft in the vicinity of Callisto's surface?

b)What is the mass of the craft?

c)What is the free-fall acceleration near the surface of Callisto?

Answer 1

a) weight is the the net force which prevents an objects from falling freely.

So, 3120 N the object descends at a constant speed (no acceleration), the weight must be: 3120 N.

b) At an upward force of 2106 N, the craft decelerates because its weight(force of g on object *mass) is greater than the upward force of the engine. The difference between these two forces is the net force on the object. (3120N-2106N = 1014N). At a force of 1014N, the object's acceleration is .39 m/s^2.

F=ma.

1014N= m (.39m/s^2)
1014N/ (.39m/s^2) = m
m= 2600 Kg.

c) We know that at 1014 N the acceleration is .39m/s^2. However, this portion is asking for the acceleration when the engine is turned off (no upward force= free fall). In other words, the acceleration with a downward force of 3120 N.

a= .39 (3120/1014)= 1.2m/s^2