A swimmer bounces straight up from a diving board and falls feet first into a pool. She starts with a velocity of 5.00 m/s, and her takeoff point is 1.30 m above the pool.

Required:
a. How long are her feet in the air?
b. What is her highest point above the board?
c. What is her velocity when her feet hit the water?

Respuesta :

Answer:

a

     t =  1.235 s

b

  [tex]h_{max} = 2.55 \ m[/tex]

c

 [tex]v = -7.10 m/s[/tex]

Explanation:

From the question we are told that

    The  initial  velocity is [tex]u = 5.0 \ m/s[/tex]

      The  take of height is  [tex]h = -1.30 \ m[/tex]

The negative sign show that the height is on the negative y-axis when the take off point is consider as the origin

Generally from the kinematic equation we have that

       [tex]s = ut + \frac{1}{2}at^2[/tex]

=>     [tex]-1.30 = 5.0 t + \frac{1}{2} (-9.8)t^2[/tex]

Here g is negative given that the swimmers jump motion is against gravity

    [tex]4.9t^2 - 5t - 1.30[/tex]

solving using quadratic formula we obtain that

    t =  1.235 s

Generally the highest point is mathematically evaluated as

      [tex]h_{max} = \frac{v^2 - u^2 }{2 * (-g) }[/tex]

Here v =  0 m/s since the velocity at the highest point is 0

   [tex]h_{max} = \frac{0^2 - 5^2 }{2 * (-9.8) }[/tex]

   [tex]h_{max} = 2.55 \ m[/tex]

Generally her velocity when the feet hits the water is mathematically evaluated from kinematic equation as

     [tex]v = \pm \sqrt{ u^2 + 2 (-g) * (-h)}[/tex]

      [tex]v = -7.10 m/s[/tex]

The  negative value of the velocity is selected because the velocity is on the negative y-axis