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STATEMENT - 1 : Two bodies projected ver...

STATEMENT - 1 : Two bodies projected vertically upward with different initial speeds cover same distances in last second of their upward journey.
and
STATEMENT - 2 : For uniformly accelerated motion, distance travelled in a time interval before coming to rest does not depend on initial speed.

A

Statement-1 is True, Statement-2 is True, Statement-2 is a correct explanation for Statement-1

B

Statement-1 is True, Statement-2 is True, Statement-2 is NOT a correct explanation for Statement-1

C

Statement-1 is True, Statement-2 is False

D

Statement-1 is False, Statement-2 is True

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question, we will analyze both statements step by step. ### Step 1: Understanding Statement 1 **Statement 1:** Two bodies projected vertically upward with different initial speeds cover the same distances in the last second of their upward journey. 1. **Let’s denote the two bodies as Body A and Body B.** - Body A is projected with an initial speed \( u_1 \). - Body B is projected with an initial speed \( u_2 \). 2. **Both bodies reach their maximum height where their final velocity \( v = 0 \).** - The time taken to reach maximum height for each body can be calculated using the equation: \[ v = u - gt \] - Rearranging gives: \[ t = \frac{u}{g} \] - Thus, the time taken for Body A is \( t_1 = \frac{u_1}{g} \) and for Body B is \( t_2 = \frac{u_2}{g} \). 3. **Distance covered in the last second of their upward journey:** - The distance covered in the last second for any uniformly accelerated motion can be calculated using: \[ S_n = u t + \frac{1}{2} a t^2 \] - For the last second, we take \( t = 1 \) second before reaching the maximum height. - For Body A: \[ S_{nA} = u_1(1) - \frac{1}{2}g(1^2) = u_1 - \frac{g}{2} \] - For Body B: \[ S_{nB} = u_2(1) - \frac{1}{2}g(1^2) = u_2 - \frac{g}{2} \] 4. **Setting the distances equal:** - Since both bodies cover the same distance in the last second: \[ u_1 - \frac{g}{2} = u_2 - \frac{g}{2} \] - This implies: \[ u_1 = u_2 \] - Therefore, the statement is true. ### Step 2: Understanding Statement 2 **Statement 2:** For uniformly accelerated motion, the distance traveled in a time interval before coming to rest does not depend on initial speed. 1. **Consider an object projected upwards until it comes to rest.** - The distance covered before coming to rest can be calculated similarly using: \[ S = ut + \frac{1}{2} a t^2 \] - Here, \( u \) is the initial speed, \( a = -g \) (acceleration due to gravity), and the time until it comes to rest is \( t = \frac{u}{g} \). 2. **Substituting into the distance formula:** - The total distance \( S \) before coming to rest is: \[ S = u \left(\frac{u}{g}\right) + \frac{1}{2}(-g)\left(\frac{u}{g}\right)^2 \] - Simplifying gives: \[ S = \frac{u^2}{g} - \frac{1}{2} \frac{u^2}{g} = \frac{u^2}{2g} \] - This shows that the distance does depend on the initial speed \( u \). ### Conclusion Both statements are true, but the second statement is not a correct explanation for the first statement. ### Final Answer - **Statement 1 is true.** - **Statement 2 is true.** - **Statement 2 is not the correct explanation for Statement 1.**
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