Chiều dài của kim phút một đồng hồ là 20cm, của kim giờ là 15cm. Tỷ số tốc độ dài của đầu kim phút so với đầu kim giờ là:

Ineed the problem dude

Iknow the first part it is the average star i am not 100% sure

The chemical reactions lab we did is typically called a "copper plating lab,  because the acid solution cleaned the pennies and made the copper look shinier;   the acid solution cleaned the paperclips and made them look like pennies;   &   the copper from the pennies was removed, and then added to the paperclips. 

Gravity, from the center of mass of the box, extending downward normal force, from the floor under the box, extending upward, equal to gravity push force, acting at a point on the box, extending in the direction of motion friction, acting at any point on the box directly opposite the push, extending directly opposite to the motion