-12+3b-1=-5-b
Combine like terms to get:
3b-13=-5-b
Add 13 to both sides:
3b= 8-b
Add b to both sides:
4b=8
Divide both sides by 4:
4b/4=8/4
b=2
Final answer
b=2
Substitute 
, so that
Then the resulting ODE in 
is separable, with
On the left, we can split into partial fractions:
Integrating both sides gives
Now solve for 
:
Answer:
Height of the fighter plane =1.5km=1500 m
Speed of the fighter plane, v=720km/h=200 m/s
Let be the angle with the vertical so that the shell hits the plane. The situation is shown in the given figure.
Muzzle velocity of the gun, u=600 m/s
Time taken by the shell to hit the plane =t
Horizontal distance travelled by the shell =u
x
t
Distance travelled by the plane =vt
The shell hits the plane. Hence, these two distances must be equal.
u
x
t=vt
u Sin θ=v
Sin θ=v/u
=200/600=1/3=0.33
θ=Sin
−1
(0.33)=19.50
In order to avoid being hit by the shell, the pilot must fly the plane at an altitude (H) higher than the maximum height achieved by the shell for any angle of launch.
H
max
=u
2
sin
2
(90−θ)/2g=600
2
/(2×10)=16km
The answer is C. 7.1 feet.
I hope this helps.
