## anonymous one year ago PLEASE HELP!!! If a baseball player hits a baseball from 4 feet off the ground with an initial velocity of 64 feet per second, how long will it take the baseball to hit the ground?

1. anonymous

hi

2. anonymous

hi

3. anonymous

can you help me?

4. anonymous

5. anonymous

10

6. anonymous

oh

7. anonymous

i thought it was easy 4th grade math sorry i'm a 6th grader.

8. anonymous

um, okay

9. anonymous

sorry bye

10. anonymous

@Vocaloid

11. DDCamp

You can use the equation: $y = y_{initial} + v_{initial}\times t - 16 \times t^2$ to find the height of the ball after t seconds. Solve the equation for y=0 and you'll get the time where the height is 0 (i.e. its on the ground)

12. anonymous

How come the direction of acceleration is not specified? You would need to identify the horizontal velocity and vertical velocity separately to know when exactly the ball will hit the ground.

13. anonymous

so the answer is $2 \pm \sqrt{17}/2$ ?

14. DDCamp

@Robert136 The question doesn't ask where, just when.

15. anonymous

You don't know.

16. DDCamp

@RosieF The quadratic equation gives you two answers, because the graph of that function would look something like this:|dw:1439947696260:dw|

17. anonymous

When the ball makes contact with ground is dependent on the direction of the hit. I get that the ball was hit at 4 feet with an initial veocity of 64f/s, however you would need to consider acceleration due to gravity with regards to the direction of velocity.

18. anonymous

How can you even assume that the ball follows pattern of hyperbola without being explicitly stated as so?

19. anonymous

This question would be invalid in Newtonian mechanics.

20. DDCamp

Because I have a degree in physics...

21. anonymous

Then you must also know that the velocity is a vector value.

22. DDCamp

From the information we're given, the best assumption is that the problem meant a vertical velocity of 64 ft/s. The horizontal velocity is irrelevant.

23. anonymous

Usually angle is stated to the horizontal

24. anonymous

can you just tell me if the answer that I got was right?

25. anonymous

There is no right answer to this question as too much assumption is involved.

26. anonymous

well is my answer hypothetically right?

27. anonymous

However for grade 10 math I would stick with that assumption that velocity was meant to the vertical. For in grade 10 math you cover parabola.

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