Daryl the delivery guy gets out of his pizza delivery truck but forgets to set the parking brake. The 2,000.-kilogram truck rolls down hill reaching a speed of 30 m/s just before hitting a large oak tree. The vehicle stops 0.72 s after first making contact with the tree. a. How much momentum does the truck have just before hitting the tree?

b. What is the average force applied by the tree?

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?