Physics: When a 58-g tennis ball is served?

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Homework Help Overview

The problem involves a 58-g tennis ball that accelerates from rest to a speed of 36 m/s over a distance of 36 cm. Participants are tasked with determining the magnitude of the net force acting on the ball, while navigating through calculations involving acceleration and force.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the use of the net force equation and the need for correct unit conversions. There are attempts to calculate time and acceleration using different equations, with some questioning the validity of their approaches and the assumptions made regarding the motion of the ball.

Discussion Status

The discussion is active, with participants providing feedback on calculations and suggesting alternative methods to find the time and acceleration. There is an ongoing exploration of the correct application of kinematic equations, and some participants express confusion about the relationships between distance, time, and acceleration.

Contextual Notes

Participants are working under the constraints of homework rules, which may limit the information they can use or the methods they can apply. There is a focus on ensuring unit consistency throughout the calculations.

triplel777
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Homework Statement



When a 58-g tennis ball is served, it accelerates from rest to a speed of 36 m/s. The impact with the racket gives the ball a constant acceleration over a distance of 36 cm. What is the magnitude of the net force acting on the ball?


Homework Equations





The Attempt at a Solution



Fnet= ma
to find a i need time
so i used v=d/t to find the time. 36=36/t so t=1sec
now to find a i used V-V_0=at so 36=a*1 so a=36
now i plugged it in
Fnet= 58g*36=2088

what am i doing wrong?
 
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You are very sloppy with your units. Go back through your calculations making sure the units are correct. I can see at least two major place where you units are incorrect. See if this fixes the answer.
 
ok so i changed the m=0.058kg, and d=0.36m
so t=0.01s which makes a=3600m/s2 so fnet= 3600*0.058=208.8. did i do a conversion wrong/
 
The speed of the ball isn't 36 m/s during the entire acceleration, but only at the end of it, so you can't use v = d/t and the time you computed is wrong.
use x = (1/2) a t^2 to find out when the ball has moved 36 cm.
 
how can i use x= 1/2 at^2 if i don't know the t or a? what do i use for t? i tried using v^2-V_0^2=2a(x-x_0) but that didnt work out?
 
triplel777 said:
how can i use x= 1/2 at^2 if i don't know the t or a? what do i use for t? i tried using v^2-V_0^2=2a(x-x_0) but that didnt work out?

You know x = 0.36m = (1/2)at^2 and v = at = 36 m/s
 
oh ok thanks its 104.4
 

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