An airplane flies horizontally at a speed of 489 km/h and drops a crate that falls into the horizontal ground below. Neglect air resistance. a) If the altitude of the plane was 715m, then how far, horizontally in meters, did the crate move as it fell to the ground?
b) What was the speed of the crate, in m/s, just before it hit the ground?

Respuesta :

Answer:

a) x= 1618.3 m

b)V=180.59 m/s

Explanation:

Speed of plane = 489 Km/h

Speed of plane = 489  x 5/18 m/s = 135.33  m/s

Horizontal velocity of crate , u  = 135.33  m/s

h= 715 m

a)

In vertical direction

[tex]h=v_ot+\dfrac{1}{2}gt^2[/tex]

The initial velocity in vertical direction =0 m/s

[tex]715=\dfrac{1}{2}\times 10\times t^2[/tex]

t = 11.95 s

So the distance travel ,x= u .t

   x = 135. 33 x 11.95

x= 1618.3 m

b)

The speed of crate V

[tex]v^2=v_o^2+2gh[/tex]

[tex]V^2=2\times 10\times 715[/tex]

v=119.58 m/s

u  = 135.33

So the resultant velocity V

[tex]V=\sqrt{v^2+u^2}[/tex]

[tex]V=\sqrt{119.58^2+135.33^2}[/tex]

V=180.59 m/s

The equation of motion is the relation between the distance, velocity, acceleration and time of a moving body.

  • a) The horizontal distance traveled by crate is  1634 meters.
  • b) The speed of the crate, in m/s, just before it hit the ground is 180.59 m/s.

What is the second equation of motion?

The equation of motion is the relation between the distance, velocity, acceleration and time of a moving body.

The second equation of the motion for distance can be given as,

[tex]s=ut+\dfrac{1}{2}at^2[/tex]

Here, [tex]u[/tex] is the initial body, [tex]a[/tex] is the acceleration of the body and [tex]t[/tex] is the time taken by it.

Given information-

The horizontal speed of the airplane is 489 km/h.

The altitude of the plane is 715 m.

Convert the horizontal speed of the airplane in meter per second by multiplying it with factor 5/18. Thus,

[tex]v_a=489\dfrac{5}{18} \\v_a=135.33\rm m/s[/tex]

  • a) The horizontal distance traveled by crate is-

The distance traveled in the vertical direction is 715 m and velocity of the airplane is 135.33 m/s.

As the initial velocity is zero for vertical direction. Thus put the value in the distance formula to find the time,

[tex]715=0+\dfrac{1}{2}9.81\times t^2\\t=12.07\rm s[/tex]

Now the horizontal distance can be given as,

[tex]s=ut\\s=135.33\times12.07\\s=1634\rm m[/tex]

The horizontal distance traveled by crate is 1634 meters.

  • b) The speed of the crate, in m/s, just before it hit the ground-

The initial velocity is zero for this case, thus use the velocity formula to find the speed of crate  as,

[tex]v^2=(u)^2+2gs\\v^2=2\times 9.81\times715\\v=118.44 \rm m/s[/tex]

The speed of the crate, in m/s, just before it hit the ground is the resultant velocity of horizontal velocity and vertical velocity. thus,

[tex]V=\sqrt{135.33^2+119.58^2}\\V=180.59 \rm m/s[/tex]

Thu, the speed of the crate, in m/s, just before it hit the ground is 180.59 m/s.

Hence,

  • a) The horizontal distance traveled by crate is  1634 meters.
  • b) The speed of the crate, in m/s, just before it hit the ground is 180.59 m/s.

Learn more about the equation of motion here;

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