If two identical balls are moving at the same speed in opposite directions do they have the same momentum or different

What is a neurotransmitter involved in mood reward, addiction, and motor behaviors?

What are the similarities & differences between a thermistor and a light dependent resistor in physics?

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?