Acceleration is defined as the change in velocity divided by the change in time. Since the velocity changed from 50 m/s to 40 m/s (-10 m/s change) in 2 seconds, then the acceleration is (-10/2) = -5 m/s^2 northward. Hope this helps!
Answer: 
Explanation:
Given
CD has a playing time of 
Initial angular speed of CD is 
Final angular speed of DC is 
Angular speed, when rpm is given
Final speed
Using equation of angular motion
Insert the values
Magnitude of angular acceleration is
I'm pretty sure it's the neutron star.
To get this we need to know how long he was traveling. To know that we need to solve for the time it took for him to hit the ground. This is given by the vertical height he started at and the equation of motion for falling objects. The position function is
Y= -(9.8/2)t^2 + 50 = 0
t=3.19s
That's how long he's in the air. When he hits the ground he stops moving forward so this is also the amount of time he was moving at 100m/s horizontally. Now use speed distance relationship
X=vt
And solve for v
100m/3.19s = 31.35m/s
