The surfer in the photo is catching a wave. Suppose she starts at the top of the wave with a speed of 1.22 m/s and moves down the wave until her speed reaches 9.07 m/s. The drop in her vertical height is 2.91 m. If her mass is 41.4 kg, how much work is done by the (non-conservative) force of the wave?

Respuesta :

Answer:

The work done by the non-conservative force is 491.43 J

Explanation:

You have to apply the Work-Energy Theorem for mechanical energy, which is:

W non-conservative force = ΔEm

Where ΔEm is the variation of mechanical energy between two points of the movement.

ΔEm= Emf-Emi

Emf: Final mechanical energy

Emi: Initial mechanical energy

Also, the mechanical energy is:

Em= Ep+Ek

Where Ep is the potential energy and Ek is the kinetic energy.

In this case, the potential energy is gravitational, due to the change in the height.

Ep= mgh (m is the mass, g the acceleration of gravity and h is the height)

Ek= 0.5mv² (m is the mass, v is the speed)

Wncf = Epf+Ekf - (Epi+Eki)

The initial mechanical energy is:

Emi= mgh + 0.5mvi²

Replacing the values of m, g, h and vi:

Emi= (41.4)(9.8)(2.91) + 0.5(41.4)(1.22)²

Emi=1211.45 J

The final mechanical energy is:

Emf = Ekf

There isn't potential energy because at the bottom of the wave the height is zero.

Emf= 0.5mvf²

Replacing m=41.4 kg and vf=9.07 m/s

Emf = 0.5(41.4)(9.07)²

Emf=1702.88 J

Therefore:

Wncf = 1702.88 - 1211.45 = 491.43 J

Lanuel

The work done by the (non-conservative) force of the wave is equal to 491.43 Joules.

Given the following data:

Initial velocity = 1.22 m/s.

Final speed = 9.07 m/s.

Height = 2.91 m.

Mass = 41.4 kg.

How to calculate work done.

In Science, work done is generally calculated by multiplying force and the vertical height or displacement experienced by an object.

Mathematically, the work done by the (non-conservative) force of the wave is given by this formula:

[tex]W=E_f-E_i\\\\W=\frac{1}{2}mv_i^2-(mgh+\frac{1}{2}mv_i^2) \\\\[/tex]

Substituting the given parameters into the formula, we have;

[tex]W=\frac{1}{2}\times 41.4 \times 1.22^2-(41.4 \times 9.8 \times 2.91+\frac{1}{2}\times 41.4 \times 9.07^2)\\\\W=1702.88-1211.45[/tex]

W = 491.43 Joules.

Read more on work done here: brainly.com/question/22599382