Cục dự trữ lương thực quốc gia cần thiết kế một số xylo hình trụ để bảo quản thóc. Biết rằng: 1. Thóc khi đưa vào bảo quản đã được làm khô đến độ ẩm 13%. Khối lượng riêng của phần chất rắn có trong hạt thóc là 1230 g/dm³. Khối lượng riêng của nước là 1g/cm³. Độ trống rỗng của khối thóc là 0,15
2. Điều kiện môi trường bảo quản là nhiệt độ 10°C, độ ẩm tương đối của không khí là 80%
3. Thể tích hữu dụng của xylo bảo quản là 80% (thể tích của khối thóc chỉ nên chiếm tối đa 80% thể tích của cả xylo). Xylo có đường kính là 3,5m
Hãy tính:
a. Khối lượng riêng của thóc
b. Chiều cao của xylo để có thể bảo quản được 8 tấn thóc

After the near spacecraft passed mathilde, on several occasions rocket propellant was expelled to adjust the spacecraft's momentum in order to follow a path that would approach the asteroid eros, the final destination for the mission. after getting close to eros, further small adjustments made the momentum just right to give a circular orbit of radius 45 km (45 × 10^3 m) around the asteroid. so much propellant had been used that the final mass of the spacecraft while in circular orbit around eros was only 545 kg. the spacecraft took 1.04 days to make one complete circular orbit around eros. calculate what the mass of eros must be.

Using a wheel and axle, a farmer is trying to lift a bucket of water from the bottom of a well. the larger wheel has a radius of 40 cm compared to the axle that has a radius of 10 cm. if a bucket of water is 50 n, then how much effort is required to raise it? 12.5 n 200 n 2 n 500 n

To understand the behavior of the electric field at the surface of a conductor, and its relationship to surface charge on the conductor. a conductor is placed in an external electrostatic field. the external field is uniform before the conductor is placed within it. the conductor is completely isolated from any source of current or charge. part a: which of the following describes the electric field inside this conductor? it is in the same direction as the original external field.it is in the opposite direction from that of the original external field.it has a direction determined entirely by the charge on its surface.it is always zero. part b: the charge density inside the conductor is: 0non-zero; but uniformnon-zero; non-uniforminfinite part c: assume that at some point just outside the surface of the conductor, the electric field has magnitude e and is directed toward the surface of the conductor. what is the charge density η on the surface of the conductor at that point? express your answer in terms of e and ϵ0