Question

1 horsepower is equal to …………..watt:
(a). 746
(b). 500
(c). 646
(d). 700

Answer 1

- Hint: Horsepower and watt both are units of power is electric and mechanics. Now, using the fact that $1H.P.=550\text{foot}\text{pound}\text{per second}$, we will solve the problem.

Complete step-by-step solution -
Now, in question we are asked to find how much watt is 1 horsepower, for that we have to convert horsepower into foot per second by using the fact,
$1H.P.=550\text{foot}\text{pound}\text{per second}$ ……………….(i)
Now, we know that $$1\text{foot}=0.3048\text{metre}$$
And $1\text{pound}\text{=}\text{4}\text{.48}\text{Newton}$
Now, substituting these values in expression (i) we will get,
$1H.P.=550\times 03048\times 4.448N/s$
$1H.P.=746N/s\Rightarrow 746\text{watt}$
As, we know that $1N/s=1\text{watt}$
Hence, the value of 1 horsepower is 746 watts.
Thus, option (a) is correct.

Additional information:
Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are the mechanical horsepower (or imperial horsepower), which is about 745.7 watts, and the metric horsepower, which is approximately 735.5 watts.

Note: Students must know the FPS and MKS unit system, and also the difference between them because by knowing that only they will be able to convert the units from MKS to FPS or vice-versa. Students should also remember the value of 1 HP in terms of watt for future usages. Students might also make mistakes in conversion of FPS to MKS and they might convert it into CGS due to which the answer will be wrong.