Answer:
No, the farmer is not able to move the mule.
Explanation:
Mass =100 kg
Force=F=800 N
The coefficient between the mule and the ground=

Static friction force,f=
Normal force=N=mg
Static friction force,f=
Using 
F<f
Static friction force is greater than applied force.
Therefore , the farmer is not able to move the mule.
You asked the question twice I answered it on the last one
Answer:
Explanation:
Comet is made by dust particles, icy particles, gases etc.
A comet has a fixed time to complete a revolution around the sun.
As a comet comes nearer to the sun, due to the heat of the sun the vapour and the icy particles becomes gases and due to the radial pressure of energy od sun, we observe a tail of comet which has vapours mainly. SI the comet is visible easily.
Ocean currents can be generated by wind, density differences in watermasses caused by temperature and salinity variations, gravity, and events such as earthquakes
Sponges have appendages jointed