Projectile Motion Problem: Tennis Ball Clearance Calculation

Click For Summary

Homework Help Overview

The problem involves projectile motion, specifically calculating the initial velocity of a tennis ball hit at an angle to clear a net. The player is positioned 12.6 meters from the net, and the ball must rise at least 0.330 meters to clear it.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the need for separate equations for horizontal and vertical motion and the elimination of time from the equations. There is uncertainty about which formulas to use and how to apply the given height requirement of 0.330 meters.

Discussion Status

Some participants have offered guidance on breaking down the motion into components and suggested using standard equations of motion. There is an ongoing exploration of how to find the initial velocity components and how to approach the calculations without reaching a consensus on the method.

Contextual Notes

Participants express confusion regarding the application of kinematic equations and the interpretation of the problem's requirements. There is a lack of explicit information about the total initial velocity, which is central to solving the problem.

m_scott
Messages
10
Reaction score
0

Homework Statement


A tennis player standing 12.6m from the net hits the ball at 3 degrees above the horizontal. To clear the net, the ball must rise at least .330m. If the ball just clears the net at the apex of its trajectory, how fast was the ball moving when it left the racquet?


Homework Equations


I tried using v2=v02+2a(x-x0)


The Attempt at a Solution


I have no clue
 
Physics news on Phys.org
welcome to pf!

hi m_scott! welcome to pf! :smile:

(try using the X2 icon just above the Reply box :wink:)

you need two equations, one for the x and one for the y direction …

then eliminate t …

what do you get? :smile:
 
I still don't completely understand. What formulas am i supposed to use? And I am not sure what to do with the .330m

I set it up as: 0(final velocity)= v02+2(-9.8)(12.6) and got 15.7 but i know that's wrong...
 
Hi m_scott.
You must see the motion of the ball as a composition of two kinds of motion: one in the horinzontal axis and another in the vertical axis.
Which kind of motion on the x axis?
Which kind of motion on the y axis?
Try to write the equations of motion for each axis.
And from it, up to you...
 
uhh? :redface: forget the final velocity …

nobody asked for it! :wink:
 
what equation should i use to find motion for the x and y axis?
 
What kind of motion do you think that has the ball on the y direction ?
 
well, you're only given s and vi and a (a = 0 for the x direction, = -g for the y direction), and you want to find t for both directions and then eliminate it …

so which of the standard constant acceleration equations do you think you should use? :smile:
 
s=v0t+(1/2)at2??

And if so, do i plug in -9.8 for a and 0 for v0?

i got 1.6s Is that for the x or y axis?
 
  • #10
m_scott said:
s=v0t+(1/2)at2??

yes :smile:
And if so, do i plug in … 0 for v0?

no, v0 will be the initial component of velocity in the y direction
 
  • #11
Ok. How do I find the initial component of velocity in the y direction? Btw, sorry for all the newb questions. This is my 3rd day in physics and I am kinda lost...
 
  • #12
total velocity times sin3°

(and the initial x component is total velocity times cos3°)

haven't you done components? :confused:
 
  • #13
But the problem doesn't give me the total velocity
 
  • #14
that's right, it asks you for the total velocity …

so call that v, and solve :wink:
 

Similar threads

  • · Replies 18 ·
Replies
18
Views
5K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
Replies
33
Views
5K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 22 ·
Replies
22
Views
5K
  • · Replies 14 ·
Replies
14
Views
11K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 7 ·
Replies
7
Views
7K