Answer:
0.74 s
Explanation:
We can solve the problem by using the following SUVAT equation:
[tex]d = ut + \frac{1}{2}at^2[/tex]
where
d = 5.0 m is the displacement
u = 7.2 m/s is the initial velocity
a = -1.1 m/s^2 is the acceleration (which is negative since it is a deceleration)
t is the time
Substituting numbers into the equation, we find:
[tex]5.0 = 7.2 t -0.55t^2\\0.55t^2 -7.2t + 5.0 = 0[/tex]
This is a second-order equation, whose solutions are given by:
[tex]t=\frac{-(-7.2) \pm \sqrt{(-7.2)^2-4(0.55)(5.0)}}{2(0.55)}[/tex]
And the solutions are
t = 0.74 s
t = 12.36 s
The solution we are looking for is the first one, because it corresponds to the first time at which the hockey puck has travelled the distance of 5.0 m, reaching the goal.
