Ahand-driven tire pump has a piston with a 2.50-cm diameter and a maximum stroke of 30.0 cm. (a) how much work do you do in one stroke if the average pressure is 2.40 ×10^{5} 5 n/m^2 2 ? (b) what average force do you exert on the piston, neglecting friction and gravitational force?

(a) you do a work on the piston: 35.34 (Joules) and (b) Average Force that you exert on the piston is: 117.81 (N)

Explanation:

We need to know that the work do it for a piston or boundary work of closed system is: where W is the work, P is the pressure and delta_V is the change in the volume. Now we need to remember that the volume for a piston is the same as: where L is the maximum stroke or length, so the piston volume is: therefore, piston's work is:. Then we are going to calculate the average force so we need to know that where P is the pressure, F is the force and A the area in this case the piston´s area, so and replacing values we get:

b.

explanation:

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia