Một vật nặng treo vào lò xo thẳng đứng. Khi ở vị trí cân bằng lò xo dãn 6cm. Lấy g = 10m/s2. Số dao động mà vật thực hiện được trong 1s xấp xỉ bằng

Adding more pulleys to a system of pulleys needed to lift an object. a. increases the force b. decreases the force c. increases the amount of work d. decreases the amount of work

Cathy is pedaling down a steep hill on her bicycle and wants to be able to coast up the next hill, which is 25 meters high, without pedaling. cathy and her bicycle have a mass of 75 kg. assuming her bicycle is 100% efficient, what would her speed have to be?

Which of the following is the main energy source for the sun? a. fission of hydrogen b. fusion of hydrogen c. fusion of helium d. fission of iron