Why Is the Initial Speed of a Ball Thrown Vertically 19 m/s?

In summary, the problem involves determining the initial speed of a ball thrown vertically and caught 3.0 seconds later by a person on a balcony 14 m above the ground. While attempting to solve the problem, the individual used the equation distance/change in time and obtained a result of 4.7 m/s. However, the correct answer is 19 m/s, which can be found using a different kinematic motion equation. The discussion also touches on the behavior of the ball's speed after leaving the thrower's hand.
  • #1
athena04
1
0
A ball thrown vertically from ground level is caught 3.0 s later by a person on a balcony who is 14 m above the ground, determine the initial speed of the ball.

When I first tried doing this problem, I tried using the speed equation of distance/change in time, so I divided 14 by 3 which gave me 4.7 m/s, but according to my study guide the answer is 19 m/s and I'm having a hard time understanding why that's the answer and what equation I would use to solve it. Any help is appreciated, thanks!
 
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  • #2
Hi athena, welcome to PF!

If you are using displacement = average velocity * time, your result is the average velocity, not the initial velocity. Can you find another equation to use from the list of the kinematic motion equations?
 
  • #3
What happens to the speed of the ball after it leaves the thrower's hand?
 

1. What is the initial speed problem?

The initial speed problem refers to a problem in physics where the initial velocity or speed of an object is unknown and needs to be calculated based on other given parameters.

2. How is the initial speed of an object calculated?

The initial speed of an object can be calculated using the equation v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time elapsed.

3. What are some examples of initial speed problems?

Examples of initial speed problems include calculating the speed of a falling object, determining the initial speed of a car in a collision, or finding the launch speed of a rocket.

4. What is the difference between initial speed and initial velocity?

The terms initial speed and initial velocity are often used interchangeably, but technically, initial velocity is a vector quantity that includes both the speed and direction of an object, while initial speed only refers to the magnitude or numerical value of the initial velocity.

5. How does air resistance affect initial speed problems?

Air resistance, also known as drag, can affect the initial speed of an object by slowing it down. This is because air resistance creates an opposing force that acts against the motion of the object, causing it to accelerate at a slower rate and reach a lower final velocity.

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