Average speed is the ratio of total distance moved by Chi in total time interval
So here we will have
Total distance = 100 m + 400 m

Total time taken = 5 min + 15 min = 20 min

now by the formula of average speed we know that



so average speed will be 1.5 km/h
The orbital radius is: 
Explanation:
The problem is asking to find the radius of the orbit of a satellite around a planet, given the orbital speed of the satellite.
For a satellite in orbit around a planet, the gravitational force provides the required centripetal force to keep it in circular motion, therefore we can write:

where
G is the gravitational constant
M is the mass of the planet
m is the mass of the satellite
r is the radius of the orbit
v is the speed of the satellite
Re-arranging the equation, we find:

Learn more about circular motion:
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Answer:
55000 W/m²
Explanation:
Parameters given:
Surface temperature, T = 1000°C
Hear transfer coefficient, h = 55 W/m²C
Convection heat transfer coefficient is given as:
h = Heat flux/Temperature
Hence, Heat Flux, q, is given as:
q = h * T
q = 55 * 1000 = 55000 W/m²C
Explanation:
As we know that relation between energy and wavelength is as follows.
E = 
This means that energy is inversely proportional to wavelength. So, more is the energy of an electromagnetic radiation less will be its wavelength.
Also, f = 
Hence, less will be the wavelength more will frequency of a radiation.
Gamma rays are the rays that have highest energy, small wavelength and highest frequency.
Thus, we can conclude that gamma rays are the electromagnetic radiation which has the highest frequency.