New Definition derivative for Horsepower

[Randy Beikmann]

I an sure we have now better definitions of 'amount of work done'. than estimating how many typical sized draft horses are required to transport some number of sacks of grain to the local brewery.

Tradition is pretty strong in industry. We still measure engine speeds in rev/minute, even though rev/second at least uses an SI unit for time, and rad/sec would be more proper still. But how many people would understand that?

At least we know that 1 horsepower = 550 ft-lbf/sec, and we can convert easily enough to watts. Even the Germans have a metric horsepower, the Pferdestärke, or PS DIN. Maybe people just still relate to a comparison to the capability of a horse.

 

[zanick]

I an sure we have now better definitions of 'amount of work done'. than estimating how many typical sized draft horses are required to transport some number of sacks of grain to the local brewery.

Actually, its not the amount of work done... that would be energy. HP-seconds, (a unit measure of work) Joules.. etc... Hp or Power, would be the rate that work is being done. ;) This is why, in the spirit of the defintinon (or one of the defnintions) of energy . "a body's capacity to do work"
HP, could be a car's (or vehicle) capacity to accelerate at any speed.

Tradition is pretty strong in industry. We still measure engine speeds in rev/minute, even though rev/second at least uses an SI unit for time, and rad/sec would be more proper still. But how many people would understand that?

At least we know that 1 horsepower = 550 ft-lbf/sec, and we can convert easily enough to watts. Even the Germans have a metric horsepower, the Pferdestärke, or PS DIN. Maybe people just still relate to a comparison to the capability of a horse.

i think its way deeper than that, its really about power's relationship and measure of accelerative forces (translational or rotational) . that rate of doing work, gets commonly confused with quantity of work done. with the right gearing, a bunch of turtles can bring those same sacks to the brewery, but it might take them a while. ;)

 

[Randy Beikmann]

i think its way deeper than that, its really about power's relationship and measure of accelerative forces (translational or rotational) . that rate of doing work, gets commonly confused with quantity of work done. with the right gearing, a bunch of turtles can bring those same sacks to the brewery, but it might take them a while. ;)

Well, you can see why my 17-chapter book doesn't tackle the subject of power until Chapter 14. It isn't nearly as obvious as torque is.

But remember that power can be used for a lot more than acceleration of mass. That's just one aspect of it.