Power: Does Mass Make a Difference?

In summary, power is an important concept in mechanics as it measures the rate at which work is done. In the scenario discussed, it was used to determine the energy consumption and the acceleration of objects with different masses. It also plays a role in determining the efficiency of energy conversion. Power is important in many applications, such as in the design of vehicles and in the measurement of wind and water power. It is typically measured in watts, which is the unit for energy per second.
  • #1
Fabian901
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If Power = Force x Distance / Time, does that mean that if we apply the same force on 2 objects with different masses and we apply the force across the same distance, the object with the lower mass will have a higher power?. The way I'm looking at this is that the object with the lower mass will have a higher acceleration (a = F/m) and therefore reach distance "D" faster than the object with the higher mass. Please correct me if I am wrong as I don't want to go to the next topic without fully understanding this concept.
Thanks in advance!
 
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  • #2
Higher power was used to accelerate the lower mass. I wouldn't say the lower mass has a higher power.
 
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  • #3
The energy consumption is the same
 
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The two masses will end up with the same kinetic energy (same force applied times distance). The smaller mass will end up at the end of travel quicker - because the acceleration will be greater. Power is rate of doing work and it is zero if no work is being done, so neither of the masses will 'have' any power at the end. They will be expending 'no power' after being launched. The energy is delivered to the smaller mass faster so the Power is higher- but for a shorter time, of course and Energy is Power times Time.
It pays to be very strict with your use of terms in Physics because they each have specific meanings and applications. Also, there are often alternative ways of approaching problems like this one. It's worth bearing in mind that this sort of problem is often the best approached by energy considerations rather than speed considerations. Here, the simple fact that Energy is the same in both cases, tells you the answer without bothering with working out the acceleration at all (which is not wrong, of course - it just saves time).
 
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I see, and why is this concept important in mechanics? How does it apply to wind energy for example? Or water power?
 
  • #6
There are lots of scenarios where it may be important. It is part of the reason why a lighter car would be faster and more efficient than a heavier one, for example.

I can't think of a reason why it would come into play with wind and hydro power though...is there some context to that question?
 
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  • #7
Fabian901 said:
I see, and why is this concept important in mechanics? How does it apply to wind energy for example? Or water power?
Which concept are you referring to? I have mentioned several. :)
 
  • #8
sophiecentaur said:
Which concept are you referring to? I have mentioned several. :)
I'm referring to the concept of power, in which scenario will it be important to calculate power? If you can give me a scenario related to mechanical engineering then that would be better :)
 
  • #9
russ_watters said:
There are lots of scenarios where it may be important. It is part of the reason why a lighter car would be faster and more efficient than a heavier one, for example.

I can't think of a reason why it would come into play with wind and hydro power though...is there some context to that question?
I have to learn the advantages and disadvantages of using wind power, water power and solar power but I'm just curious as to how they would measure power in wind energy. Perhaps its simply the rate at which kinetic energy of the air is converted into electrical energy but I'm not 100% sure
 
  • #10
Fabian901 said:
I'm referring to the concept of power, in which scenario will it be important to calculate power? If you can give me a scenario related to mechanical engineering then that would be better :)

I guess you don't watch the F1 motor racing?
 
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  • #11
PeroK said:
I guess you don't watch the F1 motor racing?
Nope, I'm more of a tennis and nba basketball fan. How would power relate to F1 racing? I've always heard the term horsepower which is equal to 746 Watts but I'm not sure what it represents. Is it simply the amount of jules transmitted per second from the engine to the wheels of the F1 car?
 
  • #12
Fabian901 said:
Nope, I'm more of a tennis and nba basketball fan. How would power relate to F1 racing? I've always heard the term horsepower which is equal to 746 Watts but I'm not sure what it represents. Is it simply the amount of jules transmitted per second from the engine to the wheels of the F1 car?

Yes, Power is Energy per second. Horsepower is a measure of power based on the power of an average horse! Try Googling it.

Note that the unit of energy is the Joule (not the jule).
 
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Fabian901 said:
I'm just curious as to how they would measure power in wind energy.
In watts, same as any other power (or horsepower if you prefer --- some might prefer Dalton-furlongs2 per fortnight3, but it's a little awkward for most of us.)

Fabian901 said:
rate at which kinetic energy of the air is converted into electrical energy
Energy type "a" to energy type "b" is an efficiency.
 
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  • #14
Power (P) is important when you are concerned with how quickly a particular job can be done, or the rate of work - for instance, how long it takes to gat a truck up a hill or a car to 100mph or how many tons of coal can be raised in an hour. That's Energy / time (Joules per second) (E/t) which has the unit of Watts.
Electrical heaters and motors are rated in Watts, to tell you the rate of heating, drilling, cutting etc.
Power in vehicles is very relevant, of course, but they tend to operate at variable speeds and acceleration so the actual output power of your engine can be anything from zero to (occasionally) maximum.
At the end of a job, the total Energy delivered will be the sum of the Pt for all the intervals of time at different output P values. That's what your Electrical Energy Meter calculates when it charges you for the Energy used or it will relate to how much furl you need to put in the fuel tank. (Naturally, the Efficiency of the engine / motor needs to be taken into account.
It is a good idea to get used to the Maths of the business; it is not a difficult bit of mathematical Physics,
 
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I see! Thanks a lot for the help everyone :)
 

1. How does mass affect power?

Mass has a direct relationship with power. The greater the mass, the more power is required to move or accelerate it. This is because mass represents the amount of matter in an object, and more matter requires more energy to move it.

2. Is power affected by the shape or size of an object?

Yes, the shape and size of an object can also affect power. An object with a larger surface area will experience more air resistance, requiring more power to move it. Additionally, the shape of an object can also impact its aerodynamics, affecting the power needed to move it through a fluid or air.

3. Can an object with less mass have more power than an object with more mass?

Yes, it is possible for an object with less mass to have more power than an object with more mass. This is because power is a measure of how quickly energy is transferred, not the amount of energy itself. So, an object with less mass but a higher velocity can have more power than an object with more mass but a lower velocity.

4. How does the speed of an object relate to its power?

The speed of an object has a direct relationship with power. The faster an object is moving, the more power is required to maintain or change its speed. This is because kinetic energy, which is related to an object's speed, is a component of power.

5. Does increasing an object's mass always decrease its power?

No, increasing an object's mass does not always decrease its power. As mentioned earlier, power is also affected by an object's speed and shape. So, if an object's mass is increased, but its speed is also increased, the power may remain the same. Additionally, if the shape of an object is changed to reduce air resistance, the power needed to move it may also decrease.

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