Work, energy, and power problem

In summary, the Queen Mary 2 is a massive cruise ship with a mass of 150,000 gross tons and electrically driven pod motors with a maximum power rating of 1.57x10^5 hp. When moving at 15.0 meters/second, the kinetic energy of the QM2 is 1.71x10^10. The work done by the ship's motors to accelerate from 0-15m/s is also 1.71x10^10. The absolute minimum time for the ship's engines to accelerate the ship to 15.0 m/s is 9.18128655x10^14 seconds. The force exerted by the ship's propellers on the water at
  • #1
1. The Queen Mary 2, whose maiden voyage was in January 2004, is a cruise ship that has a mass of 150,000 gross tons (which equals 1.52×108 kg, about three times that of the Titanic). Her electrically driven pod motors have a maximum power rating of 1.57×105 hp, or 117 MW. (a) What is the kinetic energy of the QM2 when she is moving at 15.0 meters/second? (b) What is the work done by the ships motors to accelerate the ship from 0-15m/s. (c) Find the absolute minimum time in which the ship's engines could accelerate her from rest up to 15.0 m/s. Ignore the drag resistance of the water, air, and so on. (d) What is the force that the ship's propellers exert on the water when the Queen Mary 2 is moving at 15.0 m/s (assume that the maximum power is used)?

a-ke= 1/2 m v^2
ke= 1.71 x 10^10

b= w= ke
w= 1.71 x 10 ^10

c- p= w/t
1.57 x10 ^5= 1.71x 10^10 t
t= 9.18128655 x10 ^14

d- no idea.
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  • #2
Please show your attempts at answering the question.

1. What is the difference between work, energy, and power?

Work is the transfer of energy that results in an object being moved over a distance. Energy is the ability to do work, and it comes in different forms such as kinetic, potential, and thermal energy. Power is the rate at which work is done or energy is transferred.

2. How are work and energy related?

Work and energy are closely related as work is the transfer of energy. When work is done on an object, its energy changes. Similarly, when an object does work, its energy changes. They both have the same units of joules (J).

3. Can you explain the concept of conservation of energy?

The law of conservation of energy states that energy cannot be created or destroyed, only transferred or converted into different forms. This means that the total energy in a closed system remains constant. In other words, the total energy before and after any transformation is the same.

4. How is power calculated?

Power is calculated by dividing the amount of work done by the time it takes to do it. The formula for power is P = W/t, where P is power in watts (W), W is work in joules (J), and t is time in seconds (s).

5. Can you give an example of how work, energy, and power are used in everyday life?

One example is riding a bike. When you pedal, you are applying a force (doing work) on the pedals, which transfers energy to the bike's wheels, causing them to move. This requires power, which is why you may feel tired after riding for a while. Another example is turning on a light bulb - the work of flipping the switch transfers energy to the light bulb, which converts it into light and heat energy.

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