Answer:
Length of copper wire, l = 785 meters
Explanation:
Given that,
Resistance of the copper wire, R = 0.172 ohms
Area of cross section, 
Resistivity of copper, 
The resistance of a wire is given by :
l = 785 meters
So, the length of the copper wire is 785 meters. Hence, this is the required solution.
Not 100% but i think it'll cause the earth to rotate slightly slower, its definitely not the last one though
Work done by a given force is given by
here on sled two forces will do work
1. Applied force by Max
2. Frictional force due to ground
Now by force diagram of sled we can see the angle of force and displacement
work done by Max = 
Now similarly work done by frictional force
Now total work done on sled
Answer:
We know that force applied per unit area is called pressure.
Pressure = Force/ Area
When force is constant than pressure is inversely proportional to area.
1- Calculating the area of three face:
A1 = 20m x 10 m =200 Square meter
A2 = 10 mx 5 m = 50 Square meter
A3 = 20m x 5 m = 100 Square meter
Therefore A1 is maximum and A2 is minimum.
2- Calculate pressure:
P = F/ A1 = 30 / 200 = 0.15 Nm⁻² ( minimum pressure)
P = F / A2 = 30 / 50 = 0.6 Nm⁻² ( maximum pressure)
Hence greater the area less will be the pressure and vice versa.
