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:
Explanation:
Let initial extension in the spring= x₀
Force on the spring = F₀
Let spring constant = k
Fo = k x₀
Fn = 3k x₀
Fn /Fo = 3
PEs0 ( ORIGINAL) =1/2 k x₀²
PEsn ( NEW) =1/2 k (3x₀)²
PEsn / PEs0 = 9
D is the correct answer!!
<span>Both
planets, Mars and the Earth are terrestrial planets. This means that their
surface is rocky, they have Mountains, canyons, valleys, ice caps..</span>