Answer:
a = 0.7267
, acceleration is positive therefore the speed is increasing
Explanation:
The definition of acceleration is
a = dv / dt
they give us the function of speed
v = - (t-1) sin (t² / 2)
a = - sin (t²/2) - (t-1) cos (t²/2) 2t / 2
a = - sin (t²/2) - t (t-1) cos (t²/2)
the acceleration for t = 4 s
a = - sin (4²/2) - 4 (4-1) cos (4²/2)
a = -sin 8 - 12 cos 8
remember that the angles are in radians
a = 0.7267
the problem does not indicate the units, but to be correct they must be m/s²
We see that the acceleration is positive therefore the speed is increasing
Answer:
Rhythmic Gymnastics
Explanation:
In general, the judges in the sports tend to be in charge for correcting and controlling the breaking of the rules in the particular sport. They are allowed to punish the competitors in accordance with the breaking of the rule, or they are there in order to determine weather a point is regular or not. In the rhythmic gymnastics though, and sports similar to it, the judges have different role, as they are in charge of determining the points earned by the competitors. This is done in a manner where every judge gives certain amount of points, or grades, and when those are summed up, the competitors get their total points.
Part A. For this part, we use two equations for linear
motion:
<span>y = y0 + v0 t + 0.5 g t^2 --->
1</span>
<span>vf = v0 + g t --->
2</span>
First we solve for t using equation 1: y0 = 0 (initial
point at top), y = 250 m, v0 = 0 (at rest)
250 = 0.5 (9.8) t^2
t = 7.143 s
Now we solve for final velocity vf using equation 2:
vf = g t
vf = 9.8 (7.143)
vf = 70 m/s
Part B. First we solve for the time it takes for the sound
to reach the tourist.
t(sound) = 250 / 335 = 0.746 s
Therefore the total time would be:
t = 0.746 s + 0.300 s
t = 1.05 s
<span>Hence there is enough time for the tourist to get out
before the boulder hits him.</span>
