Một vật có khối lượng 30(kg) đặt trên sàn buồng thang máy. Cho g = 9,8(m/s2
). Tính lực nén của vật lên sàn trong các trường
hợp sau:
a) Thang máy lên đều.
b) Thang máy bắt đầu đi lên với gia tốc 0,5(m/s2
).
c) Thang máy bắt đầu hạ xuống với gia tốc 0,5(m/s2
).
d) Thang máy rơi tự do.

The passage that directs air to the lungs is called a. diaphragm. b. larynx. c. bronchi. d. pharynx.

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

An engine undergoes a cycle as shown in the diagram. during a complete cycle the work done by the gas is 28.5×103 j and the energy transferred thermally out is 99.4×103 j. there are 1.5×1024 gas molecules and they have three active degrees of freedom. 6. (6 pts) during which process(es) is energy transferred thermally into the gas? a. 1→2 b. 2→3 c. 4→1 d. 1→2 and 4→1 e. none of the above