A car has $900,000$ Joules of kinetic energy while it is travelling at $30\frac{m}{s}.$ Find the mass of the car.

A person in a canoe which is initialty at rest, throws an oar out of the canoe. The $0\mathrm{.}70kg$ oar is thrown horizontally $($parallel to the water surface$)$ with a speed of $6\mathrm{.}0\frac{m}{s}.$ The person and canoe have a total mass of $60kg.$ Neglect effect of water and air resistance.

a$)$ What is the total momentum of the person, oar, and canoe before the throw?

b$)$ What is the momentum of the oar after the throw?

c$)$ Assuming conservation of momentum, what is the recoil speed of the persontcanoe?

Ice skater A has momentum $300kg\frac{m}{s}$ pointing east. Ice skater $B$ has momentum $400kg\frac{m}{s}po{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}$ing north. The ice skaters collide and hold onto each other $($so that they move together as a single point$).$ The combined mass of the ice skaters is $100kg.$

a$)$ If the $x-$axis points east, what is the $x$ component of the velocity of the skaters after collision?

b$)$ If the $y-$axis points north, what is the $y$ component of the velocity of the skaters after collision?

c$)$ What is the speed of the skaters after collision?