• Support PF! Buy your school textbooks, materials and every day products Here!

Help me figure out where this equation was derived

  • Thread starter d3111
  • Start date
  • #1
1
0
1. Homework Statement

A placekicker must kick a football from a point 36.0 m (about 40 yards) from the goal, and half the crowd hopes the ball will clear the crossbar, which is 3.05 m high. When kicked, the ball leaves the ground with a speed of 23.0 m/s at an angle of 46.0° to the horizontal.

I have completed the problem correctly but was told to find time by t= delta x / (vi *costheta)

Where is this equation derived from is what i'm asking?

thanks
 

Answers and Replies

  • #2
Mentallic
Homework Helper
3,797
94
The time (t) it takes for something with uniform speed (u) to complete some displacement ([itex]\Delta x[/itex]) is given by [tex]t=\frac{\Delta x}{u}[/tex]. But the problem is that the uniform speed isn't quite the initial velocity of the ball. The ball is projected at an angle to the horizontal, so can you figure out what the horizontal velocity of the ball is?
 

Related Threads for: Help me figure out where this equation was derived

Replies
1
Views
2K
  • Last Post
Replies
2
Views
4K
  • Last Post
Replies
1
Views
6K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
3
Views
1K
Replies
2
Views
1K
Replies
4
Views
1K
Top