In the high jump, the kinetic energy of an athlete is transformed into gravitational potential energy without the aid of a pole. Find the minimum speed must the athlete leave the ground in order to lift his center of mass 1.65 m and cross the bar with a speed of 0.75 m/s.

Respuesta :

Answer:

The answer to your question is v₁ = 5.74 m/s

Explanation:

Data

v₁ = ?

h₁ = 0 m

v₂ = 0.75 m/s

h₂ = 1.65 m

g = 9.81 m/s²

Formula

                mgh₁   +  1/2mv₁²   =   mgh₂  +  1/2mv₂²

mass is not consider (if we factor mass, it is cancelled)

                        gh₁ + 1/2v₁²  =   gh₂  +  1/2v₂²

Substitution

                        (9.81)(0) + 1/2v₁² = (9.81)(1.65) + 1/2(0.75)²

Simplification

                                 0    +  1/2v₁² = 16.19 + 0.28

Solve for v₁

                                            1/2v₁² = 16.47

                                                 v₁² = 2(16.47)

                                                 v₁² = 32.94

Result

                                                v₁ = 5.74 m/s

Minimum speed must 5.74 m/s in order to lift his center of mass 1.65 m and cross the bar with a speed of 0.75 m/s.

Given here,

v₁ - initial velocity = ?

h₁ - initial height = 0 m

v₂ - final velocity = 0.75 m/s

h₂ - final height = 1.65 m

g - gravitational acceleration = 9.81 m/s²

The speed can be calculated by using the formula,

[tex]\bold { mgh_1 + \dfrac 12 mv_1^2 = mgh_2 + \dfrac 12mv_2^2}[/tex]            

factor the mass,

 [tex]\bold { gh_1 + \dfrac 12 v_1^2 = gh_2 + \dfrac 12v_2^2}[/tex]

put the values in the formula, and solve it for V1

[tex]\bold { (9.81)(0) + \dfrac 12v_1^2 = (9.81)(1.65) + \dfrac 12(0.75)^2}\\\\\bold { \dfrac 12v_1^2 = 16.19 + 0.28}\\\\\bold { \dfrac 12v_1^2 = 16.47}\\\\ \bold {v_1^2 = 2(16.47)}\\\\\bold {v_1^2= 32.94}\\\\\bold { v_1 = 5.74\ m/s}[/tex]

Therefore,  minimum speed must 5.74 m/s in order to lift his center of mass 1.65 m and cross the bar with a speed of 0.75 m/s.

To know more about kinetic energy,

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