A paving truck with a mass of kg drives in a straight line at 2.5 m/s and dumps kg of gravel on the road, taking negligible time. What is the speed of the truck after dumping the gravel?
A figure skater whose mass is 75 kg moves at 6.2 m/s towards his 50-kg-mass partner. The skater’s partner is moving at 5.5 m/s, in the same direction as the skater. When the skater catches up with his partner, he picks her up, without exerting any horizontal forces on his skates. What speed does the skater move at while he is lifting his partner?