Lee majors, a professional stuntman, is preparing to run off a dock and dive into a large kayak. the stuntman has a mass of 80.8kg and the kayak has a mass of 29.9kg. if lee dives horizontally with a velocity of 5. what is his velocity in ms immediately after he jumps into the kayak? to simplify things, ignore any velocities in the y-direction.

4.01 m/s  
The is a conservation of momentum problem. The stuntman's momentum plus that of the kayak will remain constant. Since the momentum of the kayak is 0 at the beginning, we need to calculate what the momentum will be the moment after the stuntman lands in the kayak. We will consider the landing to be a non-elastic collision. 
Initial momentum 
80.8 kg * 5.50 m/s = 444.4 kg*m/s
 Total mass of stuntman and kayak
 80.8 kg + 29.9 kg = 110.7 kg
 Speed of kayak and stuntman
 444.4 kg*m/s / 110.7 kg = 4.014453478 m/s

  Rounding to 3 significant figures gives 4.01 m/s

The masses of the objects and their densities

Aform of energy that is reflected or emitted from objects in the form of electrical and magnetic waves that can travel through space. there are many forms of  electromagnetic  energy including gamma rays, x rays, ultraviolet radiation, visible light, infrared radiation, microwaves and radio waves.