Rotational Motion of a baseball

AI Thread Summary
A major-league pitcher throws a baseball rotating at 1560 RPM towards home plate, covering 18.5 meters at an average speed of 40.2 m/s. To determine how many revolutions the ball makes during its trip, one must first calculate the time it takes to reach home plate. The rotational frequency remains constant due to conservation of momentum, allowing for the calculation of total revolutions based on time. The discussion highlights confusion around rotational motion concepts and the need for clearer instruction on the topic. Understanding the relationship between rotational speed and translational distance is crucial for solving the problem.
manuel60
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Homework Statement


A major-League pitcher throws a baseball towards home plate. the ball rotates at 1560 rpms,and it travels 18.5 meters to the plate at an average translational speed of 40.2m/s.how many revolutions does the ball make during this trip?

Homework Equations

The Attempt at a Solution


(2)(pi)(1560)/60=163.362818
 
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manuel60 said:

Homework Statement


A major-League pitcher throws a baseball towards home plate. the ball rotates at 1560 rpms,and it travels 18.5 meters to the plate at an average translational speed of 40.2m/s.how many revolutions does the ball make during this trip?

Homework Equations

The Attempt at a Solution


(2)(pi)(1560)/60=163.362818
What's the 2π for?

The question asks how many revolutions the ball makes during its trip to home plate. You didn't even calculate how long it takes the ball to make this trip.
 
I have trouble with rotational motion so I am honestly not sure what I am doing?
sorry I have a horrible teacher all she does is give us work and notes and doesn't actually teach
 
manuel60 said:
I have trouble with rotational motion so I am honestly not sure what I am doing?
sorry I have a horrible teacher all she does is give us work and notes and doesn't actually teach
Terrible, but irrelevant.

If an object rotates at 10 revolutions per minute (RPM), how many revolutions does it make in one minute? In ten minutes?

You don't need a world-class physicist to teach you this.
 
Because of the momentum conservation (during the motion only the weight acts on the ball but it's torque is 0) the ball maintain its frequency of rotation during it's journey, the frequency is given by the number of revolutions n divided by time, you have to get n
Since you have f the only thing you need to get n is the time of the journey, this is a parabolic motion, you have info on the horizontal axis
 
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