Why are levers important?

Answer 1

Levers allow a large turning force to be generated from a smaller force;

Since, Moment(Turning effect) = F x d

Therefore, a lever can result in a large turning force since the force you supply to the lever is multiplied by distance.

This makes some tasks easier such as using a screwdriver to pry open a paint tin. If you tried to open the tin with your bare hands it would be difficult, but by using a lever the force you apply is increased due to the length of the lever, d. Using a longer lever, increases d, and in turn increases the turning effect, making the task easier again.
Activation and stream control.

Like pulling the lever to open the trap door.

Also like your computerchip opening it's tiny lever to let electricity flow through.

Answer 2

They are torque multipliers, translating a small force applied over some distance or a large angle,to a large force applied for a short distance or small angle. This means for example that a heavy piece of machinery can be controlled withrelatively little effort by its human operator.

Mathematically, Work Done = Force X Distance.

Toothed gears work on the same principle.

Answer 3

A lever is a device that is used to lift and move a heavy object. It works by changing a large force moving through a small distance to a smaller force moving through a larger distance.