Question

If a hockey player starts from rest and accelerates at a rate of 2.1 m/s2 how long does it take him to skate 30m

Answer 1

Hello!

Let us apply the time function of space, in the uniform uniform motion (UUM)

Formula: $S = S_{o} + V_{o}* t + a* \frac{t^2}{2}$

Data:
S (Final position) = 30 m
So (Initial Position) = 0 m
Vo (Initial velocity) = 0 m/s
t (time) = ? (in seconds)
a (acceleration) = 2.1 m/s²

Solving:
$S = S_{o} + V_{o}* t + a* \frac{t^2}{2}$
$30 = 0 + 0*t + 2.1* \frac{t^2}{2}$
$30 = \frac{2.1t^2}{2}$
$30*2 = 2.1t^2$
$60 = 2.1t^2$
$2.1t^2 = 60$
$t^2 = \frac{60}{2.1}$
$t^2 \approx 28.5$
$t \approx \sqrt{28.5}$
$\boxed{\boxed{t \approx 5.3\:s}}\end{array}}\qquad\quad\checkmark$

Answer:
C. 5.3s