Question

The velocity of bullet is reduced from 200m/s to 100 m/s while traveling through a wooden
block of thickness 10 cm. The retardation, assuming it to be uniform will be:
(1) 10 x 104 m/s2 (2) 1.2 x 104 m/s2 (3) 13.5 x 104 m/s2 (4) 15 x 104 m/s2​

Answer 1

The velocity of bullet is reduced from 200m/s to 100 m/s while traveling through a wooden

block of thickness 10 cm. The retardation, assuming it to be uniform will be:

(1) 10 x 104 m/s²

(2) 1.2 x 104 m/s²

(3) 13.5 x 104 m/s²

(4) 15 x 104 m/s²

________________________

Hope it will be helpful :)⚡

Answer 2

Answer:

$\bigstar{\bold{Option\:4:\:15\times 10^{4}\:m/s^{2} }}$

Explanation:

$\Large{\underline{\underline{\bf{Given:}}}}$

• Initial velocity (u) = 200 m/s
• Final velocity (v) = 100 m/s
• Distance travelled (s)= 10 cm

$\Large{\underline{\underline{\bf{To\:Find:}}}}$

• Retardation (a)

$\Large{\underline{\underline{\bf{Solution:}}}}$

→ By the third equation of motion, we know that

 v² - u² = 2as

→ First we have to convert 10 cm to m

For converting cm to m, divide it by 100

10/100 = 0.1 m

→ Substituting the datas in the above equation,

  100² - 200² = 2 × a × 0.1

  10000 - 40000 = 0.2 a

  a = -30000/0.2

  a = -150000 = - 15 × 10⁴ m/s²

→ Here acceleration is  negative since it is retardation.

$\boxed{\bold{Acceleration=15\times 10^{4}\:m/s^{2} }}$

→ Hence option 4 is correct

$\Large{\underline{\underline{\bf{Notes:}}}}$

→ The three equations of motion are :

• v = u + at
• s = ut + 1/2 × a × t²
• v² - u² = 2as