Question

A bullet of 10g strikes a sand bag at a speed of 10^3 m/sec and gets embetted after travelling 5cm.Calculate the resistive force excerted by the sand on the bullet??

Answer 1

Answer:

Resistive force will be    F = 10^5 N

t = 10 ^-4 secs

Explanation:

Given A bullet of 10 g strike the sand bag at a speed of 1000 m/s and gets embedded after travelling 5 cm. calculate

(a)Resistive force exerted by sand on bullet.

(b)Time taken by bullet to come to rest.

Given mass of bullet m = 10 g = 0.01 kg

Speed v = 1000 m/s

distance s = 5 cm = 0.05 m

We know that F = ma  

and v^2 = u^2 – 2as  

or a = v^2 – u^2 / 2s

    Now F = m (v^2 – u^2 / 2s)

 = 0.01 x (1000^2 – 0 / 2 x 0.05)

 Resistive force will be    F = 10^5 N

Now time taken to come to rest will be

S = (u + v / 2) t

So t = 2s / u + v

 = 2 x 0.05 / 1000

 t = 10 ^-4 secs

Answer 2

Here it is given that,

Mass of Bullet = 10g = 0.01kg

Initial Velocity (u) = 1000m/s

Distance covered (s) = 5cm = 0.05m

Final Velocity (v) = 0m/s

We have to find,

Force exerted by sand on bullet.

Formulae used,

➢ v² - u² = 2as

➢ F = ma

Now,

➢ So, acceleration = - 10⁷m/s²

Therefore,

So, The Force exerted by sand on bullet is - 10⁵N

➢ Note :- Negative Sign implies force is acting opposite to the Direction.