Question

5) A body of mass 5 kg initially at rest is subjected to a force of 29N.What is the kinetic energy
acquired by the body at the end of 10 s. ​

Answer 1

Given :

Mass of the body = 5 kg

Applied force = 29N

Initial velocity = zero

To Find :

Kinetic energy of body after 10 s.

Solution :

❖ First of all we need to find acceleration of the body.

• As per newton's second law of motion force is measured as the product of mass and acceleration.

Mathematically, F = m a

By substituting the given values;

➙ F = m a

➙ 29 = 5 × a

➙ a = 29/5

➙ a = 5.8 m/s²

♦ Final velocity of body can be calculated by using first equation of kinematics$.$

• v = u + at

» v denotes final velocity

» u denotes initial velocity

» a denotes acceleration

» t denotes time

➠ v = u + at

➠ v = 0 + (5.8)(10)

➠ v = 58 m/s²

♦ Kinetic energy of the body :

➛ k = 1/2 mv²

➛ k = 1/2 × 5 × (58)²

➛ k = 16820/2

➛ k = 8410 J = 8.41 kJ

Answer 2

Answer:-

The kinetic energy acquired by the body at the end of 10s is 8.41 kJ

Explanation:-

Given:-

• Mass of body ( m ) = 5 kg

• Initial velocity ( u ) = 0

• Force applied ( F ) = 29 N

• Time ( t ) = 10s

To find:-

What is the kinetic energy acquired by the body at the end of 10 s ?

Solution:-

We know that,

⠀⠀${\underline{\boxed{\sf{Acceleration,a=\dfrac{Force}{Mass\:of\:the\:body}}}}}$

$\sf{:\implies Acceleration=\dfrac{29}{5}\:m/s^{2}}$

$\sf{:\implies Acceleration=5.8\:m/s^{2}}$

Now,

Velocity of body at the end of 10s ,

⠀⠀⠀⠀⠀⠀⠀⠀${\underline{\boxed{\sf{v=u+at}}}}$

$\sf{:\implies Velocity=0+5.8×10\:m/s^{2}}$

$\sf{:\implies Velocity=5.8×10\:m/s^{2}}$

$\sf{:\implies Velocity=58\:m/s^{2}}$

Now,

Kinetic energy acquired by the body ,

⠀⠀⠀⠀⠀⠀⠀${\underline{\boxed{\sf{K.E=\dfrac{1}{2}×m×v^{2}}}}}$

$\sf{:\implies Kinetic\:energy=\dfrac{1}{2}×5×(58)^{2}\:J}$

$\sf{:\implies Kinetic\:energy=\dfrac{1}{2}×5×3364\:J}$

$\sf{:\implies Kinetic\:energy=\dfrac{16820}{2}\:J}$

$\sf{:\implies Kinetic\:energy=8410\:J}$

$\sf{:\implies Kinetic\:energy=8.41\:kJ}$

The kinetic energy acquired by the body at the end of 10s is 8.41 kJ