Question

a bullet of mass of 80 gram has its kinetic energy equal to 800 joule find the speed of the bullet​

Answer 1

mass(m) = 80 gm = 80/1000 = 0.08 kg

KE = 800 J

Speed (v) =?

Now, KE = 1/2mv²

or, 800 = 1/2×0.08 v²

or, 800 = 0.04 v²

or, v²= 800/0.04

or, v² = 20,000

or, v =√(20,000)

= 141.42 m/s

Answer 2

• speed of bullet = 141.4 m/s

${ \bold{ \underline {\underline{Step \: by \: step \: explanation:}}}}$

${ \bold{ \underline {\underline{Given:}}}}$

a bullet of mass of 80 gram has its kinetic energy equal to 800 joule.

${ \bold{ \underline {\underline{To \: find:}}}}$

The speed of the bullet,I,e.. velocity

${ \bold{ \underline {\underline{Required \: formula:}}}}$

Kinetic energy = (1/2 )(m)(v)^2

${ \bold{ \underline {\underline{values:}}}}$

• Kinetic energy = 800 joules
• mass = 80 grams = 0.08 kg

${ \bold{ \underline {\underline{Solution:}}}}$

By substituting the values in above given formula, we get:

$KE= \frac{1}{2} m {v}^{2} \\ </p><p>800 = \frac{1}{2} \times 0.08 \times {v}^{2} \\ \frac{800 \times 2}{0.08} = {v}^{2} \\ \frac{8 \times {10}^{2} \times 2}{8 \times {10}^{ - 2} } = {v}^{2} \\ 2 \times {10}^{2} \times {10}^{2} = {v}^{2} \\ 2 \times {10}^{4} = {v}^{2} \\ v = \sqrt{2 \times {10}^{4} } \\ v= \sqrt{2} \times {10}^{2}$

we know that,

• value of square root of 2 is 1.414

By substituting value of root 2 we get :

$v = 1.414 \times {10}^{2} \\ \boxed{v = 141.4 \: m/s}$

Hope it helps you ✌️