Question

17.A force of 5 N changes the velocity of a body from 20 m/s to 30 m/s in 5 sec. How much force is required to bring about some change in 2 sec?.​

Answer 1

Answer:

10N

Explanation:

Acceleration = 30-20 / 5 = 2m/s^2

Mass = Force/Acceleration = 5/2 = 2.5kg

New a = 30-20 / 2 = 5m/s^2

New force = ma = 2.5*5 = 10N

Answer 2

Given:-

• Force = 5N

• initial velocity = 20m/s

• final velocity = 30m/s

• time = 5 sec.

To Find:-

• Force required to bring changes in the interval of 2 sec.

Solution:-

by using 1st kinematical equation,

⇒ v = u + at

⇒ 30 = 20 + a(5)

⇒ 10 = 5a

⇒ a = 10/5

∴ a = 2 m/s²

We know that,

→ F = ma

→ 5 = m(2)

∴ m = 2.5 kg

Now, find the acceleration in the interval of 2 sec by using 1st kinematical equation:-

⇒ v = u + at

⇒ 30 = 20 + a(2)

⇒ 10 = 2a

⇒ a = 10/2

∴ a = 5 m/s²

Now, use the formula of force to find the required answer.

→ F = ma

→ F = 2.5 × 5

∴ F = 12.5 N

hence, the required answer is 12.5 N

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