Question

The velocity of a bullet is reduced from $200\text{m/s}$ to $100\text{m/s}$ while travelling through a wooden block of thickness $10\text{cm}$. Assuming it to be uniform, the retardation will be:

• A. $15\times {10}^4{\text{m/s}}^2$
• B. $10\times {10}^4{\text{m/s}}^2$
• C. $12\times {10}^4{\text{m/s}}^2$
• D. $14.5{\text{m/s}}^2$

Answer 1

The correct option is A $15\times {10}^4{\text{m/s}}^2$

Using the formula, ${\text{v}}^2={\text{u}}^2+2\text{as}$

$(100{)}^2=(200{)}^2-2\text{a}\times \frac{10}{100}$

$2\text{a}\times \frac{10}{100}=(200{)}^2-(100{)}^2=300\times 100$

$\text{a}=\frac{3\times {10}^5}{2}=15\times {10}^4{\text{m/s}}^2$