Question

A rocket of initial mass 115 kg (including all the contents) has an engine that produces a constant vertical force (the thrust) of 1930 N . Inside this rocket, a 18.5-N electrical power supply rests on the floor.
A) Find the initial acceleration of the rocket.

B) When the rocket has reached an altitude of 120 m, how hard does the floor push on the power supply? Neglect the air resistance.

Answer 1

Answer:

Part (i) the initial acceleration of the rocket is 6.98 m/s²

Part(ii) the floor pushes on the power supply at 120m altitude by a force of 31.68 N

Explanation:

Part (i) the initial acceleration of the rocket.

For the rocket to accelerate, the force applied to it must overcome gravitational force due to its own weight.

$F_{Net} = M(a+g)\\\\1930 = 115(a+9.8)\\\\a +9.8 =\frac{1930}{115} \\\\a +9.8 = 16.78\\\\a = 16.78-9.8\\\\a = 6.98 \frac{m}{s^2}$

Part(ii) how hard the floor pushes on the power supply at 120 m altitude

At 120 m height, the acceleration of the rocket is 6.98 m/s², which is the same as the power supply.

given force on power supply;

F = 18.5 N

Applying Newton's second law of motion, the mass of the power supply = 18.5/9.8

= 1.888 kg

The force on power supply at this altitude = m(a+g)

                                           = 1.888(6.98 +9.8)

                                           = 1.888(16.78)

                                           = 31.68 N

Therefore, the floor pushes on the power supply at 120 m altitude by a force of 31.68 N