How Do You Calculate the Initial Speed of the Second Stone?

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SUMMARY

The problem involves calculating the initial speed of a second stone thrown downward after the first stone is dropped from a height of 47.0 meters. The first stone, dropped from rest, takes a certain time to reach the water, while the second stone is thrown 1.48 seconds later and both stones hit the water simultaneously. To solve for the initial speed of the second stone, one must first determine the time it takes for the first stone to fall using the equation of motion for free fall, which is influenced by gravitational acceleration.

PREREQUISITES
  • Understanding of kinematic equations for free fall
  • Knowledge of gravitational acceleration (9.81 m/s²)
  • Ability to manipulate equations to solve for unknown variables
  • Familiarity with concepts of initial velocity and time intervals
NEXT STEPS
  • Study the kinematic equation: \( d = v_i t + \frac{1}{2} a t^2 \)
  • Learn how to calculate time of flight for free-falling objects
  • Explore the concept of relative motion in physics
  • Practice problems involving multiple objects in motion with different initial conditions
USEFUL FOR

Students studying physics, particularly those focusing on kinematics and motion, as well as educators looking for examples of problem-solving in free fall scenarios.

kmshowalter
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Homework Statement



A stone is dropped into a river from a bridge 47.0 m above the water. Another stone is thrown vertically down 1.48 s after the first is dropped. Both stones strike the water at the same time. What is the initial speed of the second stone?

Homework Equations


The Attempt at a Solution



What I'm not understanding is how to find the initial velocity of the first stone. I'm pretty sure you need that to figure out the initial speed of the second stone. At first I thought I needed to do 47/1.48s but when I did that I realized I didn't understand what that number would even represent. I know that I need an equation that will give me the time for both stones.
 
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kmshowalter said:

Homework Statement



A stone is dropped into a river from a bridge 47.0 m above the water. Another stone is thrown vertically down 1.48 s after the first is dropped. Both stones strike the water at the same time. What is the initial speed of the second stone?

Homework Equations





The Attempt at a Solution



What I'm not understanding is how to find the initial velocity of the first stone. I'm pretty sure you need that to figure out the initial speed of the second stone. At first I thought I needed to do 47/1.48s but when I did that I realized I didn't understand what that number would even represent. I know that I need an equation that will give me the time for both stones.

When something is "dropped" it is assumed to be released from rest. When something is "thrown" it is given some initial velocity.
 

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