A uniform metre rule is pivoted at its centre. A 20g mass is placed at the 10 cm mark and a 50g mass at the 40cm mark. At what mark must a second 50g mass be placed for the system to be in rotational balance?​

Which best represents the law of conservation of mass ?

Which of these is constant for all types of electromagnetic radiation in a vacuum? select one: a. wavelength b. frequency c. photon energy d. amplitude e. velocity

A14 kg rock starting from rest free falls through a distance of 5.0 m with no air resistance. find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earths velocity. earth mass is 6.0 * 10^24 kg. show your work assuming the rock earth system is closed.