Một khối lập phương bằng nhôm cạnh 20cm nổi trên thuỷ ngân. Hỏi khối nhôm sẽ chìm xuống bao nhiêu khi nhiệt độ tăng từ 270K đến
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a) 1.57 m/s
The sock spins once every 2.0 seconds, so its period is
T = 2.0 s
Therefore, the angular velocity of the sock is
The linear speed of the sock is given by
where
is the angular velocity
r = 0.50 m is the radius of the circular path of the sock
Substituting, we find:
B) Faster
In this case, the drum is twice as wide, so the new radius of the circular path of the sock is twice the previous one:
At the same time, the drum spins at the same frequency as before, therefore the angular frequency as not changed:
Therefore, the new linear speed would be:
And substituting,
So, we see that the linear speed has doubled.
At the player's maximum height, their velocity is 0. Recall that
which tells us the player's initial velocity is
The player's height at time is given by
so we find their airtime to be