Physics, asked by appuanu2852, 7 months ago

7.A bullet of 10 g strikes a sand bag at a speed of 1000m/s and gets embedded after traveling 5cm.(a) Calculate the resistive force exerted by the sand on the bullet.(b) Time taken by the bullet to come to rest. *

Answers

Answered by rsagnik437
24

Given:-

→Mass of the bullet = 10g

→Initial velocity of the bullet = 1000m/s

→Distance travelled by the bullet = 5cm

To find:-

→The resistive force exerted by the sand on the bullet.

→Time taken by the bullet to come to rest.

Solution:-

•Final velocity of the bullet will be zero as it finally comes to rest after embedding into the sand bag.

Firstly, let's convert the mass of the bullet from g to kg and distance travelled by the bullet from

cm to m.

=>1g = 0.001kg

=>10g = 10(0.001)

=>0.01kg

=>1cm = 0.01m

=>5cm = 5(0.01)

=>0.05m

By using the 3rd equation of motion,we get:-

=>-u² = 2as

=>0-(1000)² = 2×a×0.05

=>a = -1000×1000/2×0.05

=>a = -10m/

Hence,we have got acceleration of the bullet as -10m/.

By using Newton's 2nd law of motion,we get:-

=>F = ma

=>F = 0.01(-10⁷)

=>F = -10N

[Here,negative sign represents

resistive force]

Now,by using the 1st equation of motion,we get:-

=>v = u+at

=>0 = 1000+(-10⁷)t

=>-1000 = -10⁷t

=>t = -1000/-10⁷

=>t = 10s

Thus:-

→Resistive force exerted by sand on the bullet is -10⁵N.

Time taken by the bullet to come to rest is 10s.

Answered by Anonymous
17

Answer:

(i) the resistive force exerted by the sand on the bullet is - 1 x 10⁵ N

(ii) the time taken by the bullet to come to rest is 1 x 10⁻⁴ s

Given Parameter :

  • mass of bullet, m = 10 g = 0.01 kg
  • speed of the bullet, v = 1000 m/s = 10³ m/s
  • distance traveled by the bullet, d = 5 cm = 0.05 m

Explanation:

(i) the resistive force exerted by the sand on the bullet

the acceleration of the bullet is given by;

→ v² = u² + 2as

→ 0 = (10³)² + a(2 x 0.05)

→ -0.1a = (10⁶)

→ -a = (10⁶) / 0.1

a = -1 x 10⁷ m/s²

The resistive force is given by;

➳ F = ma

➳F = (0.01)(-1 x 10⁷)

F = - 1 x 10⁵ N

(ii) the time taken by the bullet to come to rest.

➝ v = u + at

➝ 0 = 10³ + (-1 x 10⁷ t)

➝ 1 x 10⁷ t = 10³

➝ t = 10³  / 10⁷

t = 1 x 10⁻⁴ s

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