Answer:
The speed of of the balloon is about 6.32 m/s
Step-by-step explanation:
Assuming all of the work done is transformed into the balloon's kinetic energy, we can use the formula for the kinetic energy to answer the question:
![E_k=(1)/(2)mv^2\\20J = (1)/(2)1kg\cdot v^2\implies v=\pm\sqrt{40(m^2)/(s^2)}\approx\pm6.32(m)/(s)](https://img.qammunity.org/2019/formulas/physics/middle-school/lw02bdvs6pu5bso6cddfejepp8ymuna8hw.png)
Speed is the absolute value of velocity, so the speed of the balloon is about 6.32 m/s