The Lone Wanderer needs to push an 80.0-kg desk a distance o…

The Lone Wanderer needs to push an 80.0-kg desk a distance of 4.00 m across a Vault floor to reach a stash of Nuka-Cola Quantum. The coefficient of kinetic friction is 0.400, making this feel like a Strength 9 challenge.   How much work does the Wanderer do to move the desk at constant speed?  

A Tesla Model Y of mass 1990 kg collides head-on with a park…

A Tesla Model Y of mass 1990 kg collides head-on with a parked Cybertruck of mass 3000 kg.  Spring mounted bumpers in each vehicle ensure that the collision is essentially elastic. After the collision, the velocity of the truck is 17 km/h in the same direction as the Model Y’s initial velocity.   What was the initial speed of the Model Y?