Một vật dao động điều hòa với biên độ 13cm, tại thời điểm ban đầu vật ở biên dương. Sau khoảng thời gian ∆t vật đi được quãng đường 136,5cm. Vậy trong khoảng thời gian 2∆t vật đi được quãng đường là bao nhiêu

The electric field between square plates of a parallel-plate capacitor has magnitude e. the potential across the plates is maintained with constant voltage by a battery as they are pulled apart to twice their original separation, which is small compared to the dimensions of the plates. the magnitude of the electric field between the plates is now equal to a)e b)e/4 c)e/2 d)4e e)2e

Asolid cylinder and a cylindrical shell have the same mass, same radius, and turn on frictionless, horizontal axles. the cylindrical shell has light-weight spokes connecting the shell to the axle. a rope is wrapped around each cylinder and tied to blocks of equal masses that are held the same height above the ground. both blocks are released simultaneously. the ropes do not slip. which block hits the ground first? or is it a tie?

What does the law of conservation of mass state?