Determine the speed of a falling object 7.8 sec after it dropped. a. 39 m/s
b. 304.2 m/s
c. 1.3 m/s
d. 78 m/s

76.4m/s

Explanation:

Given parameter:

Time taken  = 7.8sec

Unknown:

Speed after it dropped  = ?

Solution:

To solve this problem, we use one of the kinematics equation:

      V  = U + gt

V is the final speed

U is the initial speed  = 0m/s

g is the acceleration due to gravity

t is the time taken

       V  = 0 + 9.8 x 7.8  = 76.4m/s

potential energy is directly proportional to height.

more height = more potential energy.

greatest increase in height = greatest increase in potential energy

where are the points with the greatest increase in height ?

has to be c-e or d-e .

b.

explanation: