Anyone can solve these numerical please.

Explanation:

2. Sum the torques about the fulcrum.

(450 N) (2 m) − (350 N) x = 0

x = 2.57 m

3. Sum the torques about the fulcrum.

(3600 N) (0.20 m) − F (0.90 m) = 0

F = 800 N

Mechanical advantage is the ratio between the load force and effort force.

MA = 3600 N / 800 N

MA = 4.5

Velocity ratio is the mechanical advantage divided by efficiency.  Assuming the lever is 100% efficient:

VR = 4.5 / 1

VR = 4.5

4. Mechanical advantage is the ratio between the load force and effort force.

MA = 900 N / 600 N

MA = 1.5

The velocity ratio is the distance moved by the effort divided by the distance moved by the load.  For a 3 pulley system, VR = 3.

Efficiency is mechanical advantage divided by velocity ratio.

e = 1.5 / 3

e = 0.50

5. Sum the torques about the fulcrum.

(-300 N) (0.10 m) + F (0.03 m) = 0

F = 1000 N

pe = weightxheight = 2000x1000=2,000,000joules

e/c, where e is its total energy