Question

a body of mass 9 kg moving with a uniform velocity of 20 m/s it is acted upon by a force at 30 N what will be its velocity after 1 second ​

Answer 1

$\Huge\underline\blue{\rm Answer}$

$\Large\red{\boxed{\sf v=13.6m/s }}$

$\Huge\underline\blue{\rm Solution}$

$\large\underline\pink{\rm Given: }$

• Mass (m) = 9kg

• Initial Velocity (u) = 20m/s

• Force (F) = 30N

• Time (t) = 1sec

$\large\underline\pink{\rm To\:Find: }$

• Final Velocity (v) = ?

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We know ,

$\LARGE{♡}$$\Large{\boxed{\sf a={\frac{v-u}{t}}}}$

$\large\implies{\sf a={\frac{v-10}{1}}}$

$\large\implies{\sf a=v-10→(eq1)}$

According to Newtons second Law :

$\LARGE{♡}$$\Large{\boxed{\sf F=ma }}$

$\large\implies{\sf F=m(v-10)}$

$\large\implies{\sf 30=9(v-10)}$

$\large\implies{\sf 30=9v-90}$

$\large\implies{\sf 90+30=9v}$

$\large\implies{\sf v={\frac{120}{9}} }$

$\large\implies{\sf v=13.3m/s}$

$\Huge\red{♡}$$\Large\red{\boxed{\sf v=13.6m/s }}$

Answer 2

The speed of the body after 1 second is 23.34 m/s.

Explanation:

Given that,

Mass of the body, m = 9 kg

Initial velocity of the body, u = 20 m/s

Force, F = 30 N

Time, t = 1 s

Let v is the final speed of the car. It can be calculated using the second law of motion as :

$F=m\times \dfrac{v-u}{t}$

$30=9\times \dfrac{v-20}{1}$

v = 23.34 m/s

So, the speed of the body after 1 second is 23.34 m/s.

Learn more :

Topic : Second law of motion

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