Biết 5dm3 có khối lượng 7,5 kg a, tính khối lượng riêng của cát
b tính thể tích của 7,5 tấn cát
c, tính khối lượng của 1 đống cát có thể tích 1,2 m3
d, tính trọng lượng của 2m3

Aspring with a mass of 2 kg has a damping constant 14 kg/s. a force of 3.6 n is required to keep the spring stretched 0.3 m beyond its natural length. the spring is stretched 0.6 m beyond its natural length and then released. find the position of the mass at any time t. (assume that movement to the right is the positive x-direction and the spring is attached to a wall at the left end.)

True or false: the cycle of seasons on the earth is caused by the tilt of the earth on its axis toward and away from the sun.

Does work output exceed work input when a machine is used? a) yes, it does, as machines create energy. b) it depends on the type of machine used. c) no, it doesn’t, as machines are inefficient. d) no, it doesn’t, as machines cannot create energy.