How do simple machines make work easier?
a.
they add energy to the work.
b.
they increase the force needed to work.
c.
they reduce the speed of work.
d.
they increase the distance over which a force is applied.
c.?

 D.  They increase the distance over which a force is applied.

Explanation:

Simple machines are basic mechanical devices which make our work easier like lever, pulley, wheel and axle, inclined plane, wedge and screw. The magnitude of the force or direction is altered using a simple machine. They increase the distance over which a force is applied. They use mechanical advantage to increase the magnitude of the force.

d₁ = displacement of tern from arctic to antarctic = 11000 miles

d₂ = displacement of tern from antarctic to arctic =   - 11000 miles

d = total displacement for the journey

total displacement for the journey is given as

d = d₁ + d₂

d = 11000 + (-11000)

d = 0 miles

t₁ = time of travel from arctic to antarctic = 3 months = 3 x 30 days = 90 days

t₂ = time of travel from antarctic to arctic = 3 months = 3 x 30 days = 90 days

t = total time of travel

total time of travel is given as

t = t₁ + t₂

t = 90 + 90

t = 180 days

average velocity is given as

average velocity = total displacement/ total time

v = d/t

v = 0/180

v = 0 miles/day

gravitational energy

electrical energy

kinetic energy

ligh energy