#1). The horizontal speed doesn't change.
The vertical speed is accelerated by gravity.
a). Gravity increases the vertical speed by 9.8m/s every sec.
After 5 sec, the car is falling (5x9.8) = 49 m/s vertically.
b). Horizontal: 49m/s ! Wow ! Almost 110 mph. No wonder he went off the cliff.
After 5 seconds, it's still 49 m/s.
c). After 5 sec, the horizontal speed and vertical-down speed are both 49 m/s.
The combination results in a velocity that points 45 degrees down from horizontal,
and its magnitude is
square root of (49² + 49²) = 49 √2 = about 69.3 m/s .