Question

Your friend drops your house keys down to you from their second floor window. If you catch them 2.4 m from where your friend dropped them, what is the velocity of the keys when you catch them?
a.
-6.9 m/s
c.
-7.2 m/s
b.
-6.5 m/s
d.
-7.4 m/s

Answer 1

Answer:

6.9m/s

Explanation:

Given parameters:

Initial velocity  = 0m/s

Height  = 2.4m

Unknown:

Final velocity  = ?

Solution:

To solve this problem, we use the kinematics equation below:

   

            v²   = u²  +  2gh

v is the final velocity

u is the initial velocity

g is the acceleration due to gravity  = 9.8m/s²

h is the height

           v²   = 0²  + (2 x 9.8 x 2.4)

           v  = 6.9m/s