Finding the magnitude of velocity vector

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Homework Help Overview

The problem involves a cricketer throwing a ball and seeks to calculate the range based on the force applied, time of application, and launch angle. The subject area includes dynamics and projectile motion.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the need to find the magnitude of the velocity vector and question how to derive it from the provided quantities. There are attempts to calculate acceleration and velocity using force and mass, as well as discussions on applying trigonometric principles to resolve components of motion.

Discussion Status

The discussion is ongoing, with various participants exploring different interpretations of the problem and the equations involved. Some guidance has been offered regarding the relationships between force, mass, and acceleration, but no consensus has been reached on the application of the range equation.

Contextual Notes

There is mention of a solution in a mock exam that may influence the discussion, and participants are questioning the applicability of the range equation given the conditions of the problem.

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Homework Statement


A cricketer throws a 147g ball by exerting a force of 7.5N for 0.84s. If the launch angle is 39 degrees from horizontal, calculate the range of the ball.

Homework Equations

The Attempt at a Solution


I have the range equation and I just need to find the magnitude of the velocity vector but I'm not sure how I'd find that with the given quantities?
 
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What is the answer given in solutions section?
 
Day3091 said:

Homework Statement


A cricketer throws a 147g ball by exerting a force of 7.5N for 0.84s. If the launch angle is 39 degrees from horizontal, calculate the range of the ball.

Homework Equations

The Attempt at a Solution


I have the range equation and I just need to find the magnitude of the velocity vector but I'm not sure how I'd find that with the given quantities?
Can you determine the acceleration ?
 
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I thought it was a=f/m = 51.02m/s^2 and then v=at for 42.86 ms^-1 I was going to use a particular formula for range

The solution in the back of the mock exam says f=ma rearranged for m x deltav/deltat

Which is then rearranged for deltav = Fdeltat / m = 42.8 ms

Trigonometry to then find the Vx and Vy components which can then be plugged into t = v-u/a giving us a time value. This completes the vertical plane suvat.

Horizontal 'range' was simply given as displacement s=vt: 42.8(cos39) x 6.78 = 225.52m

upload_2017-6-9_20-58-45.png

When would this equation for range be applicable? It's defined as 'the displacement in the x-axis when the y-axis displacement is 0.' I imagine there is still some displacement for this scenario even though it doesn't end in the y axis? Making this equation irrelevant?
 

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