A runner decreases his velocity from 20 m/s to 10 m/s in 2.0 s. What was his average acceleration?

Prompta snowboarder stands at the top of a hill and decides to see if he can increase his speed on his next trip down the slope.describe one thing the snowboarder could do to incrlase his speed on the slope. explain why this would cause his speed toincrease relate one of newton's laws to this problem.

Aboxcar traveling at 12 m/s approaches a string of 5 identical boxcars sitting stationary on the track. the moving boxcar collides and links with the stationary cars and they all move off together along the track. what is the final speed of the cars immediately after the collision? (you may take the mass of each boxcar to be 18,537 kg.)

Consider an ordinary, helium-filled party balloon with a volume of 2.2 ft3. the lifting force on the balloon due to the outside air is the net resultant of the pressure distribution exerted on the exterior surface of the balloon. using this fact, we can derive archimedes’ principle, namely that the upward force on the balloon is equal to the weight of the air displaced by the balloon. assuming that the balloon is at sea level, where the air density is 0.002377 slug/ft3, calculate the maximum weight that can be lifted by the balloon. note: the molecular weight of air is 28.8 and that of helium is 4.