contestada

If a 1.3 kg ball is dropped from the top of a 33.7 meter building what is its potential energy before it is dropped?
B) What is the maximum velocity of the ball in problem 1 just before it hits the ground?
C) How much kinetic energy does the ball in problem 1 have after it has fallen 10 m down the building?

Respuesta :

Answer:429.338 J; 25.7 m/s; 127.4 J

Explanation:

Given

mass of ball m=1.3 kg

Height of building H=33.7 m

(a)Potential Energy before dropping [tex]=mgH=1.3\times 9.8\times 33.7=429.338\ J[/tex]

(b)Velocity Just before hitting the ground

[tex]v=\sqrt{2gH}=\sqrt{2\times 9.8\times 33.7}=25.7\ m/s[/tex]

(c)After falling 10 m

Here initial velocity is zero

using [tex]v^2-u^2=2as[/tex]

Here,

[tex]v=\text{final veloity}[/tex]

[tex]u=\text{Initial velocity}[/tex]

[tex]a=\text{acceleration due to gravity}[/tex]

[tex]s=\text{displacement}[/tex]

Putting values

[tex]v^2-0=2\times 9.8\times 10\\v=14\ m/s[/tex]

So, kinetic energy  [tex]\dfrac{mv^2}{2}=\dfrac{1.3\times 196}{2}=127.4\ J[/tex]