Question

For how long a force of 100N acts on a body of 20kg to gain a velocity bof 100 m/sec ?A)40 secB)5 secC)10 secD)20 sec​

Answer 1

Answer:

(D) is correct option. 20 sec.

Explanation:

Given that,

• Force, f is 100 N.
• Mass of body, m is 20 kg.
• Final velocity, v is 100 m/s.
• Initial velocity, u is 0 m/s

We know,

• F = ma

Put all values :

$\longrightarrow$ 100 = 20 × a

$\longrightarrow$ a = 100/20

$\longrightarrow$ a = 5

Acceleration is 5 m/s².

We also know,

• a = v-u/t

Put all values:

$\longrightarrow$ 5 = 100-0/t

$\longrightarrow$ 5 × t = 100

$\longrightarrow$ t = 100/5

$\longrightarrow$ t = 20

Thus,

Time is 20 seconds.

Answer 2

Given : For how long a force of 100N acts on a body of 20kg to gain a velocity of 100 m/sec?

• 40 sec

• 5 sec

• 10 sec

• 20 sec

Need to Find : Time taken

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★ Cᴏɴᴄᴇᴘᴛ :

According to the question, here we are provided with the Force applied which is 100 N, mass given is 20 kg and the speed or velocity is 100 m/s. Now, using Newton's second law of motion we can get the answer.

★ Sᴏʟᴜᴛɪᴏɴ :

Given Data :

☞ Force = 100 N

☞ Mass = 20 kg

☞ Final Velocity (v) = 100 m/s

As there are no data given on initial velocity so let's assume that it starts from rest. So, as it starts from rest no motion is gained

☞ Initial velocity (u) = 0 m/s

Formula :

❍ Newton's Second Law : F = ma ❍

Here,

F represents Force

m represents mass

a represents acceleration

Calculation Begins :

➥ F = ma

As we know that acceleration (a) is (v - u)/t

So, putting a = (v - u)/t we get

F = m(v - u)/t

➥ 100 = 20(100 - 0)/t

➥ 100 = 20 × 100/t

Cross multiplying we get

➥ 100 × t/100 = 20

➥ t = 20

Time taken is 20 sec

• Option D is correct