Question

Avinash can run with a speed of $8\,m/s$ against the frictional force of $10\,N$ , and Kapil can move with a speed of $3\,m/s$ against the frictional force of $25\,N$ . Who is more powerful?
A) Avinash
B) Kapil
C) Both are equally powerful
D) None

Answer 1

This is a pretty easy question from the topic Work, Power and Energy. You can easily approach the solution to this question by simply finding out the powers of both Kapil and Avinash and comparing them to find out who is more powerful. Remember to find out Power and nothing else is needed to solve the question.

Complete step by step answer:
We will be trying to solve the question exactly as told in the hint section of the solution to this question. Firstly, we will find out the force exerted by both, Avinash and Kapil. Then, we will use that to find out the power of both, Avinash and Kapil. And finally, we will compare the powers of both and find out who is more powerful.
To find power, we will need to use the following formula:
$P = Fv$
Where, $P$ is the power,
$F$ is the force exerted or applied by the body and,
$v$ is the velocity with which the body is moving.
Let us check Avinash’s power first:
Avinash is moving with velocity, ${v_A} = 8\,m/s$ against a frictional force of $10\,N$
To move with a constant velocity against a force, Avinash must also apply the same amount of force in opposite direction, thus, we can say that:
${F_A} = 10\,N$
Now, we can calculate the power of Avinash as:
${P_A} = \,{F_A}{v_A}$
Now, we will substitute the values that we found out:
${P_A} = 10 \times 8 \\\ {P_A} = 80\,W \\\$
Now that we have found out the power of Avinash, we will find the power of Kapil next.
In Kapil’s case:
Kapil is moving with a velocity, ${v_K} = 3\,m/s$ against a frictional force of $25\,N$ .
This means that Kapil is also exerting the same amount of force in the opposite direction.
Hence, we can write:
${F_K} = 25\,N$
Now, we can calculate the power of Kapil as:
${P_K} = {F_K}{v_K}$
Now, we will substitute the values that we found out for Kapil’s case:
${P_K} = 25 \times 3 \\\ {P_K} = 75\,W \\\$
We can clearly see that the power of Avinash is $5{\kern 1pt} W$ more than that of Kapil. Hence, Avinash is more powerful than Kapil.
Hence, option (A) is the correct answer to the question.

Note: Many students follow the wrong approach of thinking that if someone is able to resist a higher amount of force and still maintain a constant velocity is the person with more power, which is a completely wrong notion.