Answer:

Step-by-step explanation:
Displacement ⇒ -40 m (the ball strikes the ground)
Initial velocity ⇒ 10 m/s
Acceleration of gravity ⇒ -10 m/s² (upward acceleration)
We can use a formula to find the time taken.





Plugging in the values.

Solve for
.


Factor the quadratic expression.

Set the factors equal to 0.


t = -2 and t = 4 (time value will not be negative in this case)
The time the ball takes to strike the ground is 4 seconds.