An air balloon is moving upward at a constant speed of 3 m/s. Suddenly a passenger realizes that she left her camera on the ground. A friend picks it up and throws it upward at 20 m/s at the instant the passenger is 5 m above the ground. (10 pts) a) Calculate the time for camera to reach passenger. b) Calculate the position and velocity of the camera when passenger catches it.

Respuesta :

Answer:t=0.3253 s

Explanation:

Given

speed of balloon is [tex]u=3\ m/s[/tex]

speed of camera [tex]u_1=20\ m/s[/tex]

Initial separation between camera and balloon is [tex]d_o=5\ m[/tex]

Suppose after t sec of  throw camera reach balloon then,

distance travel by balloon is

[tex]s=ut[/tex]

[tex]s=3\times t[/tex]

and distance travel by camera to reach balloon is

[tex]s_1=ut+\frac{1}{2}at^2[/tex]

[tex]s_1=20\times t-\frac{1}{2}gt^2[/tex]

Now

[tex]\Rightarrow s_1=5+s[/tex]

[tex]\Rightarrow 20\times t-\frac{1}{2}gt^2 =5+3t[/tex]

[tex]\Rightarrow 5t^2-17t+5=0[/tex]

[tex]\Rightarrow t=\dfrac{17\pm \sqrt{17^2-4(5)(5)}}{2\times 5}[/tex]

[tex]\Rightarrow t=\dfrac{17\pm 13.747}{10}[/tex]

[tex]\Rightarrow t=0.3253\ s\ \text{and}\ t=3.07\ s[/tex]

There are two times when camera reaches the same level as balloon and the smaller time is associated with with the first one .

(b)When passenger catches the camera time is  [tex]t=0.3253\ s[/tex]

velocity is given by

[tex]v=u+at[/tex]

[tex]v=20-10\times 0.3253[/tex]

[tex]v=16.747\ m/s[/tex]

and position of camera is same as of balloon so

Position is [tex]=5+3\times 0.3253[/tex]

[tex]=5.975\approx 6\ m[/tex]