91影视

To determine how high above the breakpoint the balloon will rise and the height of the breakpoint from the ground, the kinematics equation for the distance or height can be used.

The initial velocity of balloon, $v_0$, is equal to 19.6 m/s

Time the balloon keeps ascending after the breakpoint$t_1=2s$.

Gravitational Acceleration is $a=g=-9.8\mathrm{m}/{\mathrm{s}}^2$. It is assumed to be negative as it is acting in the downward direction and upward direction is considered as positive.

Time required to reach ground $t_2=8.00s鈥�2.00s=6s$,

The formula for the height is,

role="math" localid="1656152167610" $h=v_{0}t+\frac{1}{2}a{t}^2$ (i)

Substitute the given information in equation (i) and calculate the height.

$$\begin{gathered} h_1=v_0{t}_1+\frac{1}{2}a{t_1}^2 \\ =19.6m/s脳2s+\frac{1}{2}\left(-9.8m/s^2\right)脳{\left(2s\right)}^2 \\ =19.6\mathrm{m}鈮�20\mathrm{m} \end{gathered}$$

Therefore, the height above the breakpoint of the balloon is$20\mathrm{m}$.

Putting the given values in the kinematic equation (i),

$$\begin{gathered} h_2=v_0{t}_2+\frac{1}{2}a{t_2}^2 \\ =19.6\frac{m}{s}脳6s+\left(\frac{1}{2}-\frac{9.8}{s^2}脳6s^2\right) \\ =58.8\mathrm{m} \\ =59\mathrm{m} \end{gathered}$$

Therefore, the height of the breakpoint from the ground is$59\mathrm{m}$.