Question

Find the kinetic energy of a ball of mass 200 g moving at a speed of 20 cm s-1
(a) 0.4 J(b) 0.004 J(c) 0.001 J(d) 0.1 J
I want the solution not one word answer , if you give proper solution , i will make you the brainiest

Answer 1

Given :-

• Mass (m) = 200 g
• Velocity (v) = 20$\sf{cms^{-1}}$

To find :-

• Kinetic energy (KE) = ?

Solution :-

• Firstly, convert mass from kg into g.

$\mapsto$ Divide the value by 1000.

$\mapsto$ Mass = 0.2 kg

• Now, convert velocity from $\sf{cms^{-1}}$ to $\sf{ms^{-1}}$

$\mapsto$ Divide the value by 100.

$\mapsto$ Velocity = 0.2 $ms^{-2}$

Formula to find Kinetic Energy

• (KE) = $\sf{\dfrac{1}{2}~mv^2}$

Put the given values :-

$= \sf{\dfrac{1}{2} \times \: 0.2 \: \times ({0.2})^{2} }$

= $\sf{\dfrac{1}{2} \times \: \dfrac{2}{10} \: \times \dfrac{2}{10} \times \dfrac{2}{10} }$

= $\sf{ 0.004 \: joule}$

• Kinetic Energy = 0.004 J

Hence, option B is correct.

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Know more :-

Kinetic Energy :-

• The energy possessed by an object due to its motion.
• Its S.I. unit is joule (J).
• It is a scalar quantity.

Velocity :-

• The distance travelled by a body in one second in a particular direction is called velocity.
• Its S.I. unit is m/s.
• It is a vector quantity.