12–139. Cars move around the “traffic circle” which is in the shape of an ellipse. If the speed limit is posted at 60 km>h, d
etermine the minimum acceleration experienced by the passengers.
(60)2
y
2
0)2 = 1
*12–140. Cars move around the “traffic circle” which is in the shape of an ellipse. If the speed limit is posted at 60 km>h, determine the maximum acceleration experienced by the passengers.
12–142. The race car has an initial speed vA = 15 m> s at
a. If it increases its speed along the circular track at the rate at = (0.4s) m> s2, where s is in meters, determine the time needed for the car to travel 20 m. Take r = 150 m.
x
Probs. 12–139/140
(60)2
y
2
0)2 = 1
*12–140. Cars move around the “traffic circle” which is in the shape of an ellipse. If the speed limit is posted at 60 km>h, determine the maximum acceleration experienced by the passengers.
12–142. The race car has an initial speed vA = 15 m> s at
a. If it increases its speed along the circular track at the rate at = (0.4s) m> s2, where s is in meters, determine the time needed for the car to travel 20 m. Take r = 150 m.
x
Probs. 12–139/140
1 answer:
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Answer:
A. The bomb will take <em>17.5 seconds </em>to hit the ground
B. The bomb will land <em>12040 meters </em>on the ground ahead from where they released it
Explanation:
Maverick and Goose are flying at an initial height of , and their speed is v=688 m/s
When they release the bomb, it will initially have the same height and speed as the plane. Then it will describe a free fall horizontal movement
The equation for the height y with respect to ground in a horizontal movement (no friction) is
[1]
With g equal to the acceleration of gravity of our planet and t the time measured with respect to the moment the bomb was released
The height will be zero when the bomb lands on ground, so if we set y=0 we can find the flight time
The range (horizontal displacement) of the bomb x is
[2]
Since the bomb won't have any friction, its horizontal component of the speed won't change. We need to find t from the equation [1] and replace it in equation [2]:
Setting y=0 and isolating t we get
Since we have
Replacing in [2]
A. The bomb will take 17.5 seconds to hit the ground
B. The bomb will land 12040 meters on the ground ahead from where they released it