11. if a ball with an original velocity of zero is dropped from a tall structure and takes 7 seconds to hit the ground, what velocity does the ball have when it reaches the ground? a. 34.3 m/s b. 156.8 m/s c. 240.1 m/s d. 68.6 m/s

The correct answer is D) 68.6 m/s

Calculation-

As per the question, the initial velocity of the ball, u = 0

Time take to hit the ground, t = 7 seconds

Here, the acceleration of the ball is the acceleration due to gravity.

Hence, acceleration, a = g =

The final velocity of the ball just before hitting the ground is calculated as-

                 V = u+ at

Putting the values in the equation, we get-

                V = 0 + gt

                   = 9.8 × 7 m/s.

                   = 68.6 m/s

Thus, ball has the velocity of 68.6 m/s when it reaches the ground.

igneous rocks are formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.  

the composition depends on the source magma. there are almost a thousand types of composition found till now.  

hope this