Does the Golf Ball Land Before, In, or After the Lake?

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Homework Help Overview

The problem involves a golfer hitting a golf ball with an initial velocity of 40 m/s at a 45-degree angle, with a lake located 100 m away and 50 m wide. The question is whether the ball lands before, in, or after the lake.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate the time of flight and horizontal distance traveled by the golf ball, initially concluding it lands before the lake. However, they later realize a potential error in their time calculation.

Discussion Status

Some participants are actively questioning the calculations and assumptions made regarding the time of flight. Acknowledgment of a mistake in the original poster's approach has led to a revised distance calculation, indicating a shift in understanding.

Contextual Notes

Participants are discussing the implications of using the correct total time for the projectile's flight and the importance of interpreting calculation results accurately.

rasen58
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Homework Statement


Golfer hits a golf ball so that it goes with initial velocity of 40 m/s at angle of 45 degrees. 100 m away is a lake that is 50 m wide. The ball will not bounce or roll when it lands. Where does the ball land?
Before, in, or after the lake.

Homework Equations


Vertical: a = (v-v0)/t
Horizontal: Δx = v0t+1/2at2

The Attempt at a Solution

[/B]
I found the time as 2.8 s using the first equation by setting v = 0 (midway in flight), and v0 = 40sin45
Then I substituted the time into the second equation along with 0 for the acceleration since there is no horizontal acceleration and v0 = 40cos45. And got 79 m, so the ball lands before the lake.
But apparently the answer is that it lands after the lake.
What did I do wrong?
 
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rasen58 said:
2.8 s
This is the time for what?
 
The time to travel halfway.
Oh... I should've used twice that to get the total time. I get 160 m now.
Thanks, my mistake.
 
Always try to keep in mind what information you get from a calculation, and what information you've been asked to find.
 
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