In a hydraulic system a force of 400N is applied to a piston of an area 0.0004 m. (a) Calculate the pressure transmitted through the rake fluid. (b) Calculate the force ofa piston of area 0.002 m that is connected to the system

The applied force is $F = 400 \, \text{N}$.
The area of the piston is $A = 0.0004 \, \text{m}^2$. (Assuming "0.0004 m" is a typo and refers to area in m$^2$).

The pressure transmitted through the fluid is $\boxed{1,000,000 \, \text{Pa}}$.

According to Pascal's principle, the pressure is transmitted equally throughout the hydraulic fluid. So, $P = 1,000,000 \, \text{Pa}$.
The area of the second piston is $A_2 = 0.002 \, \text{m}^2$. (Assuming "0.002 m" is a typo and refers to area in m$^2$).

The force on the piston of area $0.002 \, \text{m}^2$ is $\boxed{2,000 \, \text{N}}$.