There is a game machine in the park that measures the instantaneous impact force. Its schematic diagram is shown in Figure (a). Visitors put on boxing gloves and hit an A that can move horizontally.

(1) According to the circuit diagram, the resistor R is connected in series with R0, and the voltage across R0 is measured with a voltmeter.

According to ohm's law, the current in the circuit:

I = u0r 0 = 1.5v 120ω= 0.0 125 a；

As can be seen from the image, when the pressure is 2000N, the corresponding resistance is R = 360ω.

Voltage across resistor r:

UR = IR = 0.0 125 a×360ω= 4.5V，

The currents everywhere in the series circuit are equal,

∴ Supply voltage:

u = U0+UR = 1.5V+4.5V = 6V；

(3) As can be seen from the image, the resistance R ′ = 600Ω when it is not impacted,

The total resistance in the series circuit is equal to the sum of the individual resistances,

∴ current in the circuit at this time:

I 1′= UR′+R0 = 6v 600ω+ 120ω= 1 120 a；

At this point, the voltmeter indicates:

u0′= I 1 r0 = 1 120 a× 120ω= 1V。

Answer: (1) The power supply voltage is 6V;

(2) When the equipment A is not impacted, the reading of the voltmeter is1v. ..