Answer:
The skydiver needs 0.71 seconds to reach 7 m/s
Step-by-step explanation:
Free Fall Motion
When an object is dropped in free air (no friction) from a certain height h, it follows a free-fall motion, whose acceleration is due exclusively to gravity. The speed at a moment t when the object is dropped (from rest) is:
![V_f=gt](https://img.qammunity.org/2021/formulas/physics/middle-school/sp00mz84d96azq6mxvap96lw9ffmn9nx4g.png)
We need to find How long does the skydiver needs to reach 7 m/s. We solve for t
![\displaystyle t=(V_f)/(g)](https://img.qammunity.org/2021/formulas/physics/middle-school/lekbi44eyn9jga9m9ytd3vk5giarbe4imk.png)
![\displaystyle t=(7)/(9.8)](https://img.qammunity.org/2021/formulas/physics/middle-school/nc10iznku1uw75zb514a2gto6zslntqchp.png)
![t=0.71\ sec](https://img.qammunity.org/2021/formulas/physics/middle-school/h0cq5bsrlic7w4cw0vvm4vjduclindexuh.png)
The skydiver needs 0.71 seconds to reach 7 m/s