91影视

The given data can be listed below as:

• The mass of the dancer is${\mathrm{m}}_1=65\mathrm{kg}$.
• The initial decelerating velocity of the dancer鈥檚 head is$\mathrm{u}=-4.0\mathrm{m}/\mathrm{s}$.
• The time taken by the dancer鈥檚 head to decelerate is$t=0.20s$.
• The mass of the head of the dancer is$m_2=65\mathrm{kg}脳9.4\%=6.11\mathrm{kg}$.

The force exerted by an object is described as the product of the mass and the acceleration of that object. The force is also inversely proportional to the time taken by that object to exert force.

The equation of the magnitude of the average force is expressed as:

$$\begin{gathered} F-m_{2}g=m_{2}a \\ F=m_2\left(a+g\right) \end{gathered}$$

Here, $F$is the magnitude of the average force, $m_2$is the mass of the dancer鈥檚 head, is the acceleration of the dancer and is the acceleration due to gravity.

As the dancer is in the air, then the acceleration of the dancer will be equal in the magnitude but opposite in the direction of the acceleration due to gravity that is $-g$.

Substitute the values in the above equation.

$$\begin{gathered} F=\left(6.11\mathrm{kg}\right)\left(\mathrm{g}-\mathrm{g}\right) \\ =\left(6.11\mathrm{kg}\right)\left(0\right) \\ =0\mathrm{N} \end{gathered}$$

Thus, the magnitude of the average force is 0N .