Bài 4: Một vật dao động điều hòa với phương trình x = 4cos(4πt - π/3) cm. a)Viết phương trình vận tốc của vật.
b) Xác định vận tốc của vật ở các thời điểm t = 0,5 (s)

Which describes an image that can be produced by a concave lens? the image is real and smaller than the object. the image is virtual and larger than the object. the image is virtual and smaller than the object. the image is real and larger than the object.

Awater balloon launcher uses an elastic band with a spring constant of 115 n/m to use thee launcher you stretch thee band back with a balloon n it the water balloons have a mass of 1.3 kg a) if you stretch the band by 0.8 m, what elastic force will the band exert? b) with the band stretched 0.8 m, how much elastic potential energy is stored in the spring? c) if you release the band, it pushes forward. what is the kinetic energy of the balloon when it reaches the natural length of the band? d) what is the speed of the balloon when it reaches the natural length of the band?

Specific heat refers to the amount of heat required to change 1 gram of a substance by degree(s) celsius