The velocity of the bullet becomes one third after it penetrates 4 cm ...
Given:
- The velocity of the bullet becomes one third after it penetrates 4 cm in a wooden block.
- The bullet stops completely after traveling at (4x) cm inside the block.
To find:
The value of x.
Solution:
Step 1: Understanding the problem
- Let's assume the initial velocity of the bullet is v.
- After penetrating 4 cm in the wooden block, the velocity of the bullet becomes one third, which means its final velocity is v/3.
- The bullet stops completely after traveling (4x) cm inside the block, which means the final velocity is 0.
Step 2: Applying the concept of velocity
- The velocity of an object is given by the formula v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time taken.
- In this case, the acceleration is constant and the time taken is not given. So, we need to use another formula to relate the velocities.
Step 3: Using the formula for velocity
- The formula relating initial velocity, final velocity, acceleration, and displacement is v^2 = u^2 + 2as, where v is the final velocity, u is the initial velocity, a is the acceleration, and s is the displacement.
- We can use this formula to find the displacement of the bullet inside the wooden block.
Step 4: Calculating the displacement
- The initial velocity of the bullet is v and the final velocity is v/3.
- The displacement is 4 cm.
- Plugging these values into the formula, we get (v/3)^2 = v^2 + 2a(4 cm).
Step 5: Simplifying the equation
- Expanding the equation, we get v^2/9 = v^2 + 8a.
- Multiplying both sides by 9, we get v^2 = 9v^2 + 72a.
- Rearranging the terms, we get 8v^2 = 72a.
- Dividing both sides by 8, we get v^2 = 9a.
Step 6: Using the concept of stopping distance
- The bullet stops completely after traveling (4x) cm inside the block.
- The final velocity is 0.
- Using the formula v^2 = u^2 + 2as, where v is the final velocity, u is the initial velocity, a is the acceleration, and s is the displacement, we get 0 = v^2 + 2a(4x).
Step 7: Finding the value of x
- Substituting the value of v^2 from the previous equation, we get 0 = 9a + 2a(4x).
- Simplifying the equation, we get 0 = 9a + 8ax.
- Rearranging the terms, we get 8ax = -9a.
- Dividing both sides by a, we get 8x = -9.
- Dividing both sides by 8, we get x = -9/8.
Step 8: Final answer
- The
The velocity of the bullet becomes one third after it penetrates 4 cm ...
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