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.

Which is not a characteristic of a heat pump? a. it is used in air conditioners. b. it uses a refrigerant. c. it requires no work. d. it reverses the normal flow of thermal energy.

How is zig zagging a form of acceleration?

Aflask with vinegar in it has a mass of 160 grams. a balloon with baking soda in it has a mass of 40 grams. the balloon is attached to the flask to seal the opening and the vinegar and baking soda mixes. the balloon inflates to a large volume. what will the total mass of the balloon and flask be after the balloon inflates? explain. a) less than 200 grams because the solid baking soda disappears. b) 200 grams, because all the atoms remain in the balloon or flask. c) more than 200 grams because the size of the balloon is so much larger. d) less than 200 grams because gases such as the one in the balloon are lighter than solids and liquids.