A bullet of 10 g strikes a sand-bag at speed of 103 m/s, and gets embedded after travelling5 cm. The time taken by the bullet to stop is [[1]] sec.

A bullet of

10 g

strikes a sand-bag at speed of

10^{3} m / s

and gets embedded after travelling

5 cm

. The time taken by the bullet to stop is

0.0001 \sec

.
Mass of bullet

m = \frac{10}{1000} = 0.01 kg

u = 10^{3} m / s

, displacement

s = \frac{5}{100} = 0.05 m

.
Third law of motion,
⇨

v² - u² = 2 as

The final velocity will be zero,
⇨

0^{2} - {(10^{3})}^{2} = 2 \times a \times 0.05

⇨

- 10^{6} = 0.1 \times a

⇨

a = - 10^{7} m / s²

The resistive force is equal to,
⇨

F = ma

⇨

F = 0.01 \times (- 10^{7})

⇨

F = - 10^{5} N

The resistive force is equal to

- 10^{5} N

.
By the first law of motion,
⇨

v = u + at

⇨

t = \frac{v - u}{a}

⇨

t = \frac{0 - 10^{3}}{- 10^{7}}

⇨

t = \frac{- 10^{3}}{- 10^{7}}

⇨

t = 10^{3 - 7}

= 10^{- 4} s

= 0.0001 s

A bullet of $10 g$ strikes a sand-bag at speed of $10^{3} m / s,$ and gets embedded after travelling $5 cm$ . The time taken by the bullet to stop is [[1]] $\sec$ .