Just to correct you - the speed of light is 3.0 x 10^5 km/sec and not 105 km/sec as given by you (maybe it was just a typing mistake from your end).
The average distance between earth and moon would be - 384,000 kms.
This is calculated by the formula -> Distance = Speed x Time.
Answer:
A. It makes astronauts weightless.
Explanation:
Gravity does not make astronauts feel weightless. Astronauts are weightless because they are orbiting at the same rate as their shuttle.
Although the force of gravity weakens as one moves away from the earth surface, it does not mean that this force is absent in orbit
- Gravitational force has a constant acceleration value near the earth surface which is commonly known to be 9.8m/s².
- It is a force of attraction tending to hold and bind bodies together so far they have mass.
- This force keeps every thing from escaping space-ward from the earth surface.
Complete question is;
Shoveling snow can be extremely taxing since the arms have such a low efficiency in this activity. Suppose a person shoveling a sidewalk metabolizes food at the rate of 800 W. (The efficiency of a person shoveling is 3%.)
(a) What is her useful power output? (b) How long will it take her to lift 3000 kg of snow 1.20 m? (This could be the amount of heavy snow on 20 m of footpath.) (c) How much waste heat transfer in kilojoules will she generate in the process?
Answer:
A) P_out = 24 W
B) t = 1470 s
C) Q = 1140.72 KJ
Explanation:
We are given;
Input Power; P_in = 800 W
Efficiency; η = 3% = 0.03
A) Formula for efficiency is;
η = P_out/P_in
Making P_out the subject, we have;
P_out = η•P_in
P_out = 0.03 × 800
P_out = 24 W
B) We know that;
Power = work done/time taken
Thus;
P_out = mgh/t
We are given;
m = 3000 kg
h = 1.20 m
Thus, time is;
t = (3000 × 9.8 × 1.2)/24
t = 1470 s
C) amount of heat wasted is calculated from;
Q = (P_in - P_out)t
Q = (800 - 24) × 1470
Q = 1,140,720 J
Q = 1140.72 KJ
Thermal equilibrium is attained and the both rods are now at the same temperature.
<h3>What is thermal equilibrium?</h3>
Two bodies are said to have attained thermal equilibrium when the two bodies at the same temperature. It should be known that when two rods are firmly attached to each other heat flows from one rod to another.
As such, after some time, thermal equilibrium is attained and the both rods are now at the same temperature.
Learn more about thermal equilibrium:brainly.com/question/2637015
