A person kicks a ball, giving it an initial velocity of 20.0 m/s up a wooden ramp. When the ball reaches the top, it becomes airborne. The ramp makes an angle of 22.0º to the ground, and the ball travels a distance of 5.00 m on the ramp. What is the maximum height the ball reaches, above the point where it was kicked, if (a) the ramp is frictionless and (b) there is a coefficient of friction of 0.150 between the ramp and the ball?

Respuesta :

Answer:

(a) Height is 4.47 m

(b) Height is 4.37 m

Solution:

As per the question:

Initial velocity of teh ball, [tex]v_{o} = 20.0 m/s[/tex]

Angle made by the ramp, [tex]\theta = 22.0^{\circ}[/tex]

Distance traveled by the ball on the ramp, d = 5.00 m

Now,

(a) At any point on the projectile before attaining maximum height, the velocity can be given by the eqn-3 of motion:

[tex]v^{2} = v_{o}^{2} - 2gH[/tex]

where

H = [tex]dsin22^{\circ} = 5sin22^{\circ}[/tex]

g = [tex]9.8 m/s^{2}[/tex]

[tex]v^{2} = 20^{2} - 2\times 9.8\times 5sin22^{\circ}[/tex]

[tex]v = \sqrt{400 - 19.6\times 5sin22^{\circ}}[/tex] = 19.06 m/s

Now, maximum height attained is given by:

[tex]h = \frac{(vsin\theta)^{2}}{2g}[/tex]

[tex]h = \frac{(19sin(22^{\circ}))^{2}}{2\times 9.8} = 2.60 m[/tex]

Height from the ground = [tex]5sin22^{circ} + 2.86 = 1.87 + 2.60 = 4.47m[/tex]

(b) now, considering the coefficient of friction bhetween ramp and the ball, [tex]\mu = 0.150[/tex]:

velocity can be given by the eqn-3 of motion:

[tex]v^{2} = v_{o}^{2} - 2gH - \mu gd[/tex]

[tex]v^{2} = 20^{2} - 2\times 9.8\times 5sin22^{\circ} - 0.150\times 9.8\times 5[/tex]

[tex]v = \sqrt{400 - 19.6\times 5sin22^{\circ} - 0.150\times 9.8\times 5}[/tex] = 18.7 m/s

Now, maximum height attained is given by:

[tex]h = \frac{(vsin\theta)^{2}}{2g}[/tex]

[tex]h = \frac{(18.7sin(22^{\circ}))^{2}}{2\times 9.8} = 2.50 m[/tex]

Height from the ground = [tex]5sin22^{circ} + 2.86 = 1.87 + 2.50 = 4.37 m[/tex]