Assignment:
Part 1
1. A circuit is built so that the current starts at a voltage source and then passes through three resistors in series before going back to the voltage source. Each resistor has a different resistance: one is 200Ω, one is 300Ω, and one is 1000Ω. You measure that the voltage across the 300Ω resistor is 4.4V. What is the total voltage provided by the voltage source?
2. A circuit is built so that the current starts at a voltage source and then branches through two parallel resistors before rejoining into a single line and returning to the voltage source. One resistor is 400Ω, and the other is 200Ω. You measure the current through the 200Ω resistor to be 50mA. What is the total current moving through the circuit?
3. True or false: Put "T" in the blank if the statement is true; put "F" in the blank if the statement is false.
a. ___ Current drops after going through a resistor (it is greater before than it is after.)
b. ___ Voltage is the same across two parallel resistors.
c. ___ To measure voltage across a circuit element, the multimeter must be connected in parallel with that element
d. ___ At any intersection in a circuit (like where a path splits into two paths or where two paths come back together into one), it is always true that the current moving into the intersection equals the current moving out of the intersection.
e. ___ For any path that the current can follow through a circuit, the individual voltage drops along that path always will add up to equal the total voltage produced by the voltage source.
f. ___ For any linear arrangement of resistors ("linear" means that you can draw the circuit paths so that they never cross over each other), it is always possible to reduce that arrangement down to a single effective resistor with a resistance that is the effective resistance of the resistor arrangement.
Part 2
1. You are given a motor to lift weights with. The maximum power that you can supply the motor with is 1.2J, and the motor has an efficiency of 50%. If you have to lift weights with a speed of .7 m/s, what is the maximum mass that the motor can lift? (Remember the equation you used in lab that related electrical power to change in potential energy, and remember that speed is simply the change in distance divided by the change in time.)
2. A block with a mass of .4kg has a specificheat of .0305 Cal/g°C. It is heated to an initial temperature of 100°C, then dropped into an insulated cup of water at a room temperature of 21°C (a setup similar to the one you used in lab). The cup has a specific heat of .215 Cal/g°C and a mass of .76kg, while the water has a mass of .82 kg with a heat capacity of 1 Cal/g°C. Once the system has reached equilibrium, what will the final temperature be?
3. You are experimenting with an ideal gas inside a piston. The gas in question is pure air. The air starts at a pressure of 1atm (1 atmosphere = atmospheric pressure at sea level) and a volume of 300 cm^3. If you decrease the volume of the gas by 50 cm^3 while keeping the temperature constant, what will your new pressure be (in atm)? Use the ideal gas law.
4. A block of mass 2.0 kg slides over a frictionless surface with a velocity of 7.3 m/s. The block experiences a totally elastic collision with a piston (remember, totally elastic means that energy will be completely conserved). The block transfers all of its kinetic energy into the piston so that it is used to compress the gas inside the piston. Assuming no friction is involved, and that there is no heat transfer between the gas inside the piston and the outside environment, what will be the change in temperature of the gas inside the piston?