The ball took half of the total time ... 4 seconds ... to reach its highest
point, where it began to fall back down to the point of release.
At its highest point, its velocity changed from upward to downward.
At that instant, its velocity was zero.
The acceleration of gravity is 9.8 m/s². That means that an object that's
acted on only by gravity gains 9.8 m/s of downward speed every second.
-- If the object is falling downward, it moves 9.8 m/s faster every second.
-- If the object is tossed upward, it moves 9.8 m/s slower every second.
The ball took 4 seconds to lose all of its upward speed. So it must have
been thrown upward at (4 x 9.8 m/s) = 39.2 m/s .
(That's about 87.7 mph straight up. Somebody had an amazing pitching arm.)
Answer:
Explanation:
Average speed = Total distance / Total time.
100 km/hr
r = 100 km / hr
t = 6 hours
d = 6 * 100 = 600 km
120 km / hr
r = 120 km / hr
t = 5 hour
d = 120 * 5
d = 600 km
Total distance = 600 + 600 = 1200 km
Total time = 5 hour + 6 hours = 11 hours.
Average speed = 1200 km / 11 hours = 109.1
C because of the positioning of the initial ray of refraction
Answer:
15.5 seconds
Explanation:
Apply Newton's second law:
∑F = ma
-12500 + 9200 = (12000) a
a = -0.275 m/s²
v = at + v₀
0 = (-0.275) t + 4.25
t = 15.5 s
It takes the boat 15.5 seconds to stop.
