A battery of ? = 2.10 V and internal resistance R = 0.600 ? is driving a motor. The motor is lifting a 2.0 N mass at constant speed v = 0.50 m/s. Assuming no energy losses, find the current i in the circuit.

(a) Enter the lower current.

(b) Enter the higher current.

(c) Find the potential difference V across the terminals of the motor for the lower current.

(d) Find the potential difference V across the terminals of the motor for the higher current.

A river has a steady speed of 0.330 m/s. A student swims upstream a distance of 1.00 km and swims back to the starting point.

(a) If the student can swim at a speed of 1.10 m/s in still water, how long does the trip take?

__________ s

(b) How much time is required in still water for the same length swim?

__________ s

(c) Intuitively, why does the swim take longer when there is a current?

This is for thermodynamics:

"The latent heat of vaporization for water at 1 atm and 100 degrees C is 2.26x10³ kJ/kg. Calculate the latent heat for water at 2 atm and 100 C by combining the heat per kg required to turn liquid water into steam at 1 atm with the heat per kg required to change the pressure of that steam from 1 atm to 2 atm at a temperature of 100 C. Treat the steam as an ideal gas, and take the molar mass of water to be M = 18.015x10^-3 kg/mol."

1. If you need to do 1.6x10^-6 J of work in order to get a charge closer to another charge, what is the increase in potential energy in J of the moved charge?

2. The work done by the electric force as a positive test charge of 3.0x10^-6 C moves from A to B is 6.0x10^-5 J. What is the difference in electric potential energy (EPE) between points B and A, in Joules? What is the potential difference (V) between points B and A?

3. A negative charge q1 = -6.0x10^-8 C has a distance of 100 m to a positive charge q2 = 6.0x10^-8 C. Two points, A and B, are on the line connecting the two charges. If A is 30 m away from q1 and B is 30 m away from q2, what is the potential difference in V between the points A and B?

4. What is the intersection angle between an electric field line and an equipotential line/surface?

A force platform is a tool used to analyze the performance of athletes measuring the vertical force that the athlete exerts on the ground as a function of time. Starting from rest, a 63.0 kg athlete jumps down onto the platform from a height of 0.690 m. While she is in contact with the platform during the time interval 0 < t < 0.8 s, the force she exerts on it is described by the function below. F = (9 200 N/s)t - (11 500 N/s2)t2

Assume the positive y-axis points upward.
(a) What was the athlete's velocity when she reached the platform?

b) What impulse did the athlete receive from the platform?

(c) What impulse did the athlete receive from gravity while in contact with the platform?

(d) With what velocity did she leave the platform?

(e) To what height did she jump upon leaving the platform?

Consider a block attached to a spring in SHM with ?o=+?/4 and T=8 with A =10m.

a) What is x(0), x(1), x(2 seconds)...? What is the equation for x(t)?

c) what is the velocity at t=0? 1 sec?...

1. You brew a mug of coffee, but it is too hot to drink! You measure the temperature of the mug of coffee and find it is 180°F. You could cool it with an ice cube, but that would dilute it. Instead, you take a cold chunk of aluminum that you just happen to have in the freezer, place it in the mug of coffee, and wait until the temperature stops changing.

(a) When you drop this 300 gram chunk of aluminum into the mug of coffee (essentially water, with a mass of 400 grams), the final temperature of the coffee is a pleasing, drinkable 150°F. What was the initial temperature of the chunk of aluminum when you took it out of the freezer? You may ignore any energy transfer to or from the mug, or the surroundings.

(b) If you used 300 grams of copper (at the same initial temperature you just calculated) instead of aluminum, then repeated the experiment as outlined above, which would be true? Explain.

A. The final temperature of the coffee would be greater than 150°F.

B. The final temperature of the coffee would be less than 150°F.

C. The final temperature would be equal to 150°F.

(c) Refer back to the initial experiment in part (a). Assume the mug and coffee start at the same initial temperature of 180 °F. If the energy transfer to or from the mug were considered, which of the following would be true? (Still ignore energy transfer to or from the surroundings.) Explain.

A. The calculated final temperature would be greater than 150°F.

B. The calculated final temperature would be less than 150°F.

C. The calculated final temperature would be equal to 150°F.

Write an essay of 1500 words, giving credible references on "How electricity and magnetism will change our future transportation." Remember to follow the APA style and provide at least five references.

The flywheel of an old steam engine is a solid homogeneous metal disk of mass M = 112 kg and radius R = 80 cm. The engine rotates the wheel at 520 rpm. In an emergency, to bring the engine to a stop, the flywheel is disengaged from the engine and a brake pad is applied at the edge to provide a radially inward force F = 125 N. If the coefficient of kinetic friction between the pad and the flywheel is μk = 0.2.

How many revolutions does the flywheel make before coming to rest?

How long does it take for the flywheel to come to rest?

Calculate the work done by the torque during this time.

if an electron travels 0.200 m from an electron gun to a TV screen in 13.0 ns, what voltage ( inV) was used to accelerate it? (Note that the voltage you obtain here is lower than actually used in TVs to avoid the necessity of relativistic corrections.)

A car start from rest and travels towards a jeep. the jeep starts from rest at the same time with the car and travels toward the car. the car and jeep is 10 km apart. if the acceleration of the jeep and the car are 4 m/s^2 and 7 m/s^2 repectively, when and where will they meet?

List how we are able to measure the age of the Universe.

In a series R-L-C circuit, R= 360 ohm , L= 0.410 H and C= 1.1*10^-2 micro F. 1.What is the resonance angular frequency of the circuit? 2. The capacitor can withstand a peak voltage of 550 V. If the voltage source operates at the resonance frequency, what maximum voltage amplitude can it have if the maximum capacitor voltage is not exceeded?

If a spacecraft has a high specific mechanical energy, what does this tell us about the size of the orbit? Why?

What is the specific mechanical energy, e, of an orbit with a semimajor axis of 42,160 km