Answer:
Average speed = distance/time
From 1 to 9 seconds:
Distance covered = 1 - 0.2 = 0.8 km
Time = 9 - 1 = 8 sec
Average speed = 0.8 km / 8 sec
Average speed = 0.1 km/s .
The average speed for the whole test is 1.6 km / 20 sec = 0.08 km/sec. A graph of speed vs time would average out as a horizontal line at 0.08 km/sec from 1 sec to 21 sec. The area under it would be (0.08 km/s) x (20 sec) = 1.6 km.
Surprise surprise ! The area under a speed/time graph is the distance covered during that time !
In closing, I want to express my gratitude for the gracious bounty of 3 points with which I have been showered. Moreover, the green breadcrust and tepid cloudy water have also been refreshing.
Explanation:
 
 
        
             
        
        
        
Answer:
955.36 seconds ≈ 16 minutes
Explanation:
Power(P) is the rate of doing work(W)
That is, P = W/t, where t is the time.
multipying both sides with 't' and dividing with 'P', we get: t=W/P
Here, W = 5.35 x 10^10 J and P = 5.6 x 10^7 W ( 1 W = 1 J/s).
Therefore , on dividing W with P, we get 955.36 seconds.
 
        
             
        
        
        
Answer:
Stable atom
Explanation:
A stable atom is one that has a balanced nuclear inter-particle force reaction as such the binding energy of a stable atom is sufficient to permanently keep the nucleus as one unit. Examples of a stable atom are the atoms of  monoisotopic elements such as fluorine, sodium, iodine, gold, aluminium, and cobalt.
In a stable atom the expected number of proton, neutron, and electron are present while in an unstable atom or radioactive atom, there are more than the expected number of neutrons or protons, such that the internal energy of the nucleus is excessive and more than the binding energy, which can lead to radioactive decay.
 
        
             
        
        
        
Answer:
20 Joules
Explanation:
Work is done whenever a force moves a body through a certain distance in the direction of the force. So, work done is the product of force and distance moved.
Therefore, we have;
 Work done = Force x distance
i.e   Wd = Fs
Given that: F = 20 N and s = 1 m, then;
Wd = 20 N x 1 m
      = 20 Nm
The work done by the father is 20 Joules(Nm).