The skier left the mountain 40m long in 10s, after which he drove horizontally to a stop of 20m, considering the two equal. Find the speed of the skier at the end of the mountain and the average speed along the way.
v0 = 0,
s1 = 40m,
t1 = 10s,
s2 = 20m,
v2 = 0;
Find: v1 -? Vav -?
With uniform motion, the distance traveled can be found from the equation:
s1 = (v0 + v1) * t1 / 2 = v1 * t / 2;
Here v0 and v1 are the body velocities at the beginning of the section and at the end;
From here we find:
v1 = 2 * s1 / t1 = 8m / s;
We can write a similar equation for the second section of the path to find the time spent on it:
s2 = (v1 + v2) * t2 / 2 = v1 * t2 / 2;
t2 = 2 * s2 / v1 = 5s;
Average speed is determined by the ratio of the total distance traveled to the time spent:
Vav = s / t,
s = s1 + s2 = 40m + 20m = 60m;
t = t1 + t2 = 10s + 5s = 15s;
Vav = 60m / 15s = 4m / s.
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