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.
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
The positively charged atmosphere attracts negatively charged spider silk, might electrostatic force play in spider dispersal, according to a recent study.
Answer: Option C
<u>Explanation:</u>
The positive charge present in upper of the atmosphere and the negative charge on planet’s surface. During cloudless skies days, the air possesses a voltage of nearly around 100 volts for each and every meter from above the ground.
Ballooning spiders process within this planetary electric field. When their silk relieve their bodies then it picks up a negative charge. This oppose the similar negative charges on the surfaces on which the spiders settles and create sufficient force to lift them into the air. And spiders can hike those forces by climbing onto blades of grass,twigs, or leaves.
The answer of this is C!!!
Ok, assuming "mj" in the question is Megajoules MJ) you need a total amount of rotational kinetic energy in the fly wheel at the beginning of the trip that equals
(2.4e6 J/km)x(300 km)=7.2e8 J
The expression for rotational kinetic energy is
E = (1/2)Iω²
where I is the moment of inertia of the fly wheel and ω is the angular velocity.
So this comes down to finding the value of I that gives the required energy. We know the mass is 101kg. The formula for a solid cylinder's moment of inertia is
I = (1/2)mR²
We want (1/2)Iω² = 7.2e8 J and we know ω is limited to 470 revs/sec. However, ω must be in radians per second so multiply it by 2π to get
ω = 2953.1 rad/s
Now let's use this to solve the energy equation, E = (1/2)Iω², for I:
I = 2(7.2e8 J)/(2953.1 rad/s)² = 165.12 kg·m²
Now find the radius R,
165.12 kg·m² = (1/2)(101)R²,
√(2·165/101) = 1.807m
R = 1.807m
