A thin and light rod of length 2.4 m is pivoted at its center and masses of 2.3 kg and 3.1 kg are hung from its two ends. Find the initial angular acceleration of the rod when the system is released from a starting position of the rod that is horizontal.

An astronaut in space cannot use a scale or balance to weigh objects because there is no gravity. but she does have devices to measure distance and time accurately. she knows her own mass is 77.4 kg , but she is unsure of the mass of a large gas canister in the airless rocket. when this canister is approaching her at 3.50 m/s , she pushes against it, which slows it down to 1.30 m/s (but does not reverse it) and gives her a speed of 2.60 m/s . what is the mass of the canister?