The ball's vertical velocity at the time it just passes over the goal is 0 m/s. Its initial vertical velocity is unknown and we denote it by 
, where 
here is the ball's initial speed. Vertically, the only force acting on the ball is gravity, which attributes a downward acceleration of 9.8 m/s^2. We expect the maximum height achieved by the ball to be 2.4 m, so we can find the initial speed by solving
Answer:
a. It always points perpendicular to the contact surface.
Explanation:
"Normal" means perpendicular. Normal forces are always perpendicular to the contact surface.
Answer:
26.5 minutes
Explanation:
When the airplane is flying due West from Denver to Reno, the due-East wind with speed of 80km/h would reduce the ground speed by 80 km/h.
Its Denver to Reno ground speed is 900 - 80 = 720 km/h
The time it takes to cover 1200km at this speed is 1200 / 720 = 1.67 hours
On the other hand, when it returns from Reno to Denver in the due-East direction, the due-East wind with speed of 80km/h would add to the ground speed by 80 km/h
Its Reno to Denver ground speed is 900 + 80 = 980 km/h
The time it takes to cover 1200 km at this speed is 1200 / 980 = 1.22 hours
The difference it flight time would be 1.67 - 1.22 = 0.44 hours or 26.5 minutes
C. Light sometimes behaves like waves and at other times like particles.
2.1 x 102
Is the correct solution for this problem
