An experimental rocket designed to land upright falls freely from a height of 2.59 102 m, starting at rest. At a height of 86.9
m, the rocket's engines start and provide constant upward acceleration until the rocket lands. What acceleration is required if the speed on touchdown is to be zero?'
1 answer:
Answer:
The acceleration required by the rocket in order to have a zero speed on touchdown is 19.96m/s²
The rocket's motion for analysis sake is divided into two phases.
Phase 1: the free fall motion of the rocket from the height 2.59*102m to a height 86.9m
Phase 2: the motion of the rocket due to the acceleration of the rocket also from the height 86.9m to the point of touchdown y = 0m.
Explanation:
The initial velocity of the rocket is 0m/s when it started falling from rest under free fall. g = 9.8m/s² t1 is the time taken for phase 1 and t2 is the time taken for phase2.
The final velocity under free fall becomes the initial velocity for the accelerated motion of the rocket in phase 2 and the final velocity or speed in phase 2 is equal to zero.
The detailed step by step solution to the problems can be found in the attachment below.
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Answer:
c. V = 2 m/s
Explanation:
Using the conservation of energy:
so:
Mgh =
where M is the mass, g the gravity, h the altitude, I the moment of inertia of the pulley, W the angular velocity of the pulley and V the velocity of the mass.
Also we know that:
V = WR
Where R is the radius of the disk, so:
W = V/R
Also, the moment of inertia of the disk is equal to:
I =
I =
I = 10 kg*m^2
so, we can write the initial equation as:
Mgh =
Replacing the data:
(5kg)(9.8)(0.3m) =
solving for V:
(5kg)(9.8)(0.3m) =
V = 2 m/s
Answer:
0.000001 kg
Explanation:
because 1 kg equal 1,000,000 milligrams
we take which equals 0.000001 kg